02-05-05, 03:33 PM
I have installed corsa exhaust and some other minor things..Anything else
we can do?Drivetrain mods,chips,etc?

02-10-05, 12:39 PM
I too am desperately seeking mods for my car. I'd love to find others who are interested in getting a little more out of a DTS. I've done a couple things to mine and I've got a few parts left to install...

First off I wanted the car to be quiet. Not a performance mod, but something that mattered to me for 100mph+ cruising. The car has 435 square feet of constrained layer dampers, a couple square feet of half inch acoustic foam, and a sound barrier product lining the floor. It's about 63 decibels at 70MPH which is pretty darned quiet.

Then I wanted more grip. I upgraded fromt he stock tires to 255/50/17 BFG G-force TA KDWS tires. These improved grip significantly.

I've purchased but not yet installed the thicker swaybars from the armored version of the car. I'm hoping for reduced body roll and some improved grip.

I'd really like more power, and the ability to stiffen the shocks at will. I'd also be up for some chassis braces to improve chassis rigidity.


03-08-05, 09:13 AM
tell me more about this lining you used and other sound deadning techniques that was my second thing to do.been looking at dynamat...and where did you get thicker swaybars..............thanks

03-08-05, 11:16 AM
Most of what I used wad dynamat extreme. I also used some acoustic foam and other such materials. Major sources of noise in the stock vehicle seem to be the roof, doors and wheelwells. After multiple layers of dynamat on all of those they are very quiet. Now the major source of noise is wind noise on the windsheild and on the side windows. I'd really like some laminated side-glass but haven't been able to find any for this car. Overall road noise was drastically improved (but I did put a LOT of the stuff on....12 of dynamat's "bulkpacks").

As for the swaybars, they are the swaybars off of the armored version of the deville. They are 18 percent larger in diameter which should result in significantly increased roll resistance. I got them through my dealer's parts department, and had to work with the parts guy to make sure I got all the required brackets and bushings.


03-08-05, 11:22 AM
So what can we do to get more power and performance? Any ideas? Also is there anyone else out there who's interested? I can't believe that there is so little discussion of performance on this forum. It's pretty weak. Personally I'd really like to see heads and cam packages, intakes, and computer programming to take advantage of it all. Forced induction would be awesome.


03-08-05, 12:40 PM
There are ported heads that are sold, but that's about it! There's not much you can do to a Northstar that's in a Cadillac. The dunebuggy guys have lots of performance parts, but they won't work with a stock Cadillac computer.

03-08-05, 12:53 PM
I've seen ported heads from two sources. The problem is that you need reprogramming capabilities. I've yet to see that available but it's not because of the caddy's computers. It's simply because no one has bothered. There a a number of tuning companies making software to reprogram almost all of the current GM computers and the same goes with most other brands. We just need to convince them to spend the time mapping out the computers in Northstar equipped cars.


STS 310
03-08-05, 01:48 PM
Thing is the engineers have pretty much squeezed out as much power as possible. What is it, 289 cubic inches? I think they have optimized the hell out of that!!

03-08-05, 02:25 PM
The output is pretty good for a naturally aspirated DOHC engine without VVT. But keep in mind that there are things that they can't do at the factory due to cost constraints. They have to leave the heads essentially as-cast, with minimal machining work. They have to use cast or stamped exhaust manifolds rather than fabricated tubular headers. They try to make the engine run on 87 octane gas, wheras I'm willing to run mine on 93 octane which allows for higher compression. They have to meet much stricter emissions than even those in states like CA, so we can run more aggressive cam profiles. They have strong regard for engine noise, leading to things like restrictive exhaust and intake. I personally don't mind a little more noise (if it sounds good) and will gladly accept it if it makes more power. So I'm not saying that the engine is underdeveloped or poorly engineer. It's just that we don't have the same constraints that the engineers have, which is why we should be able to make a fair amount more power. Then if you consider forced induction (a supercharger or a turbocharger) there's no reason we couldn't have northstars producing well over 400 hp in a perfectly driveable package.


03-08-05, 02:54 PM
Dood, if you want 400 H.P., you need the Tornado Fuel Saver cuz it will double your H.P. and triple your M.P.G. for only $80!!!!!11!!1!!

Umm, yes, I'm kidding. Don't anybody ever buy one of those pieces of crap for any price.

Seriously, though, forced induction would help, but the OBD-II computer issue is yet to be solved. Organize people to put pressure on the chip guys. Show them that there's money to be made and they'll do it.

03-08-05, 03:10 PM
They're probably too busy making them for the new RWD Northstar!

03-08-05, 04:44 PM
mcowden love the joke about the tornado. LOL Is it possible to make an engine similar to the northstar in design but just increase the displacement? Maybe make it a litre bigger in size. This thought comes about because with the aurora they just shrunk the 4.6 to a 4.0. Why cant they increase the size a bit maybe by just .6 litres to put out a lot more power. I know there not going to make a new engine just because of this post but I think it is a reasonable thought.

03-09-05, 09:16 AM
Well, I'm interested in all of this as well, as I just purchased a Deville Touring Sedan myself.. Lyman.. You spent quite a bit on that noise-proofing.. Is there really a big difference? I mean, when you shut the door, can you tell? ...as opposed to just shutting the door before? When I get into a Lexus LS and shut the door, I hear almost nothing from the outside... Did you do all the installation? What might it cost to have it done?

Regarding performance, I haven't yet played around with my DTS, but I will soon. I'm interested in performance upgrades as well.. Maybe we can email one of the vendors and see what they think...

03-09-05, 12:25 PM
You could build your own Tim Allen DTSi, if you have the proper funds to do so. Here's the link. http://www.caranddriver.com/article.asp?section_id=26&article_id=3639&page_number=1

His DTS is making about 398hp, but I don't remember how much torque.

It's a shame, that they never really went ahead with his idea, of selling them in the dealership. That would have been pretty cool.

03-09-05, 01:17 PM
Well, I'm interested in all of this as well, as I just purchased a Deville Touring Sedan myself.. Lyman.. You spent quite a bit on that noise-proofing.. Is there really a big difference? I mean, when you shut the door, can you tell? ...as opposed to just shutting the door before? When I get into a Lexus LS and shut the door, I hear almost nothing from the outside... Did you do all the installation? What might it cost to have it done?

Regarding performance, I haven't yet played around with my DTS, but I will soon. I'm interested in performance upgrades as well.. Maybe we can email one of the vendors and see what they think...

Congrats on the DTS.

03-09-05, 02:13 PM
The DTSi was an ok effort. Personally I like the broad aproach they took, dealing with suspension, rolling stock, structure and power. That makes for a nicer car across the board. However I don't think the engine tuning was sufficient. It was a good start, and I'd be happy to have headers and a valve job but for a factory backed effort it was a little weak. That being said, I think this sort of performance is well within our reach, and would be worth the effort. Ported heads already exist. The exhaust system they used (minus the headers) is available from corsa. Stiffer swaybars are available from GM. I'm not sure about the stiffer springs. There's a nice intake available from volant. What I'd really like to see is a supercharger or a turbo. Unfortunately hood clearance is an issue for any supercharger other than a centrifugal (which I don't really like.) A turbo is harder to design. So unless we get a lot of really enthusiastic people it looks like forced induction won't be available for a while.

I know of a couple of companies that could develop tuning software for the northstar and they could probably be convinced if there were enough demand. Go to HPtuners.com and post on their forum about a desire to reprogram these cars. I've been nagging them for a while now but more voices won't hurt.

This section of the forum is "Northstar Performance and Technical." It would be nice to live up the title and start doing some performance work.


03-09-05, 02:19 PM
The soundproofing work did wonders for the car. When you close the door you can hear and feel a difference. If you knock on the roof from the outside it sounds like you're rapping your knuckles on concrete (that's not an exaggeration). Sound levels at 70 MPH are about 63 decibles which is better than any production car I've ever seen. Most people are amazed by it. I however just notice new noises. Now that the car is quieter the sound of the wind on the windshield (which wasn't really discernable before) is annoying. But when I drive my Lincoln I'm reminded of the difference. When I got the caddy it was about as quiet as the lincoln. Now that I'm used to the caddy, every time I drive the lincoln I keep thinking I've got a window or a door open. Overall it makes the driving experience a lot more pleasant. I can converse at a lower volume, and I can hear the stereo better. Also, dynamatting around the speaker housings improved the response so the stock system sounds a lot better


03-09-05, 08:41 PM
I hooked the corsa exhaust on my dts and let me tell you it sounds goooooooooooood

Soundslike a new vette when rap that thing out in first

well worth the money

03-09-05, 08:59 PM
A supercgarger has already been designed and tested for the northstar. It's made by XMS Racing. They have a link on CaddyInfo.com. The problem, is that they couldn't get anybody to reprogram the PCM, to adjust for the added power. If you have an OBDI car, than it will work just fine, as long as you prgram a new chip with the right settings. The OBDII computers used by Cadillac, are very hard to get into, to reprogram. It is possible to reflash them with new settings, but the equipemt is very, very expensive. It's not the same as an LS1, or LT1. Those, you can load the LS1/LT1 edit program on your laptop, plug it into the car, and go. It's just not that simple with the Northstar.

This is the Northstar Performance and Technical Section, but you have to remember that these cars have the same amoutn of aftermarket parts, as a Yugo. Thre just isn't enough interest, for cmpanies to take it seriously. If half of all Cadillac owners wanted a supercharger, I guarantee you, that I'd have one on my car already. It's just not like that though. There's only a hand full of owners, that would really be interested in superchargring their Cadillac's. That's why there's no real aftermarket for these cars.

03-09-05, 11:29 PM
I don't mean to offend anyone here but I've never been terribly impressed by that supercharger project. Any project that starts without a solid fuel management plan is suspect in my book. I've worked on development of forced induction systems and fuel management is usually one of the first three questions you answer before you start working. Also I don't think that a centrifugal blower is the idea supercharger for the northstar. Of course I'm glad that someone is working on stuff for these cars and I give them all the respect for going ahead with the development of it. As for fuel management, if they just want to get it to work, they could probably make it happen using a rising rate fuel pressure regulator, or an auxilliary injector system, or a piggyback computer. These solutions (while somewhat less elegant than reprogramming the OEM computer) can often be used to supply the correct amount of additional fuel without the OEM computer even realizing.

It's true that there aren't many performance parts for the car, which is one of the reasons for the lack of enthusiasm, which in turn is responsible for the lack of performance products. It's a chicken and egg scenario which is often hard to solve. Fortunately we've got people on both sides of the situation who seem willing to invest effort into solving it. Companies like XMS take the risk of doing development work. And we know there are at least some Northstar owners who are willing to shell out the cash for the end products. The problem is that the parts developers need to have a solid understanding of what people will be willing to buy before they can justify the capital involved in developing it. And if they are mislead then they will lose money. In the case of the XMS blower I think it was headed in slightly the wrong direction, as the style of the supercharger is less likely to appeal to the slightly more conservative crowd of caddy owners who might be more inclined to go after a roots blower mounted in place of the intake manifold.

So identifying the products that we, as northstar owners, really want and would be really willing to buy would make it easier to develop parts. Once there are a few popular performance parts out there and people who are interested in performance realize that there's actually something availabe there will be more aftermarket activity which begets more products. That's how the ball starts rolling.


03-10-05, 12:25 AM
The problem with a roots type supercharger, is the lack of space. The hood sits almost on top of the engine cover, leaving very little space for any supercharger. A turbo setup, is also hard because of the lack of space for additional exhaust and intake piping. Domestic Performance was looking into building higher flowing exhaust manifolds, and some other stuff, but there weren't enough people interested. The last time I spoke with them about it was about a year ago. Even the Centrifugal supercharger, used in XMS's design required that it be placed on the back of the engine, and driven by a pulley and shaft, due to the lack of space, and design of the engine compartment. I think the ultimate upgrade would be the mating of an engine such as the LS1, or LS6 to a built up 4T80E transmission. This of course would require significant modification, but would certainly cure the power, and aftermarket parts problem. Although I hate to admit it, the Northstar does have it's limitations. Personally, I don't know how reliable the head bolt on the LD8/L37 versions would be, with forced induction. There would have to be a effective way of strengthening the bolts, so that they could stand up to the increased pressures, especially since some might still use it as a daily driver.

03-10-05, 12:46 AM
I searched high and low a while back for reasonable mods for my DTS... not much out there. I think most of the people who own them are not interested in such mods.. I am actually surprised there is a good aftermarket exhaust system for it.
I have debated wether ornot to go for the Corsa exhaust.. I am afraid it might hurt my resale because of sound level.

Have you really noticed a true performance gain, not just good sound, worthy of the cost?

03-10-05, 08:37 AM
Scott.. Did you do the sound-proofing yourself? I couldn't possibly undertake a project like that.. How much would it cost me to have it done? Any idea? I'm really interested. One of my favorite things about the Lexus LS is how quiet it is. I'd love to have that in my DTS...

Otherwise.. You guys have more to your advantage than you realize.. Contact these companies and tell them to come here. We can start a topic about this and have these companies chime-in on what they think. We probably have a whole lot of people here that would be interested in getting more performance out of their Northstar engine.. However, I'm 100% positive that most people interested would still want their car to be a daily driver. Very, very, very few people buy a non-v-series Cadillac and intend on only using it for racing.. If these companies can build something that'll add performance but still allow the car to drive mannerly on a daily basis, they should find plenty of interest here...

03-10-05, 10:39 AM
Sal's right in that we have an advantage already. What's needed is a demand for performance parts for these cars. We, here at this forum, can help to create and communicate that demand. Like I said before, it's all about picking the right mods....ones that people will really buy.

Regarding the supercharger....I agree that hood clearance is an issue. However, if the supercharger replaced the intake manifold it might just fit. Another option is side mounting it. Turbos are a better option because there's some placement flexibility. I think a turbo system could be designed for the car but it'd take someone with some good plumbing design skills.

I think one of the most important things for us now is the ability to reprogram the computer, so head on over to that site I mentioned and speak up. I see Sal has already visited.

Regarding the insulation on my car.... I did some of it myself, but the majority of the installation I had done by a person I know who works in an audio shop doing custom installs. I was really nervous about doing it myself because it involved stripping the entire interior of the car (except the dash) and I was afraid I'd never get it back together right. Having seen it done (and having subsequently disassembled most of the interior of my car on my own for one reason or another) I think I could do it myself but I'd want to count on the car being out of commission for about a week or two. It took this guy about one full work week, working full time to get it all in there. But this was a hell of a lot of dynamat. It's 3 layers thick on all major surfaces. I'm sure 1 or 2 layers would be more than sufficient but I like overkill. Total cost would depend on the price you got the dynamat for (you might consider an alternative) and on labor cost if you chose to have it professionally installed. To get you started on an estimate, I used 12 Dynamat-Extreme bulk packs. I've seen prices in the 90-110 dollar range. Then add labor. I think doing it to the extent that I did is really a case of diminishing returns. Doing the roof, doors and floor with 1-2 layers will help you a lot. After that it's really an issue of wind noise on the glass (which I've been trying to solve for a while.) I'm also looking at injectable foam for the pillars, which I feel are another problem area.


03-10-05, 08:01 PM
cant really tell about performance i bought a used system with 3000 miles on it so i only have 500 bucks in it.......Im trying to find a dyno in town to check it.Will let you know

03-10-05, 08:51 PM
LymanSS, what website are you reffering too. You mentioned that Sal had already looked at it, but I went over your posts, and did not see a link. I might have missed it. Can you post a direct link to this site? Thanks.

03-10-05, 10:10 PM
www.hptuners.com (I haven't read the new posts in this thread yet. I'll be back...)

03-10-05, 11:01 PM
That looks like a great product, but my big question is how well will it work with my Cadillac. WIll I be able to tune all the same parameters that someone with an LS1 would be able too? Or will it be more limited, due to the complexity iof the programming in the computer itself. I guess I'll send them an email, and ask them if it will work.

03-10-05, 11:23 PM
The HP Tuners software doesn't currently support the northstar, but there's no reason it wouldn't. Contrary to the belief of some cadillac owners the software in the PCM of a cadillac isn't especially advanced or complex relative to other engine management computers from GM. So presumably if HP Tuners offered support for the northstar they would be able to offer the same features and tunability that they offer on the LS1.


03-10-05, 11:33 PM
That's the problem. Nobody wants to write a tuning program for the Northstar. I guess if 50 or so of us all emailed them at once, they might do it. Most of these companies are currently busy working on other engines, like the LS2. Do you know if we asked them, whether or not they might consider it? Their program looks really nice, and it would be great if they could write one for us Northstar owners. What do you think, would they do it?

03-11-05, 12:24 AM
RE:Sound Dampening

I used to co-own a shop, Speed and Sound Concepts, years ago. We under took one of the largest Dynomat jobs at that time (1995). I was a 300ZX Turbo 2+2.

Most Dynomat jobs are done for sound competition cars, this one was done for a prominant dentist for no other reason than he wanted his Z to be as quiet as his Mercedes.

The car was decibled before and after the job along with the Mercedes. We doubled to triple layered the entire car, and I mean the entire car. It really isn't that hard to do but is very labor intensive.. just lable and mark where everything goes and use the baggie system for fastening hardware.

We took the fenders off the car and dynomated them, the plastic inner fenderwells, we used a dynomat under hoodliner, we did the entire dash, floorboards, doors, door panels, roof, everything in double, triple or sometimes more layers. We filled all the voids with Great Stuff foam.

The job took 3 weeks, we used $5k worth of Dynomat and billed $3k in labor. Dynomat picked up some of the tab if I recall.

The car was remeasured and the difference was incredible. I cannot remember the exact numbers but I do remember we came surprisingly close to that of the Mercedes. The customer was very pleased but I also remember him saying he though it would be a lil quieter... weirdo!

Dynomat is an awesome product.

My DTS is pretty quiet when it comes to road noise, but the wind noise is a bit aggravating.. especially from the rear passenger windows, sunroof, and side rearview mirror areas. Dynomat won't solve those problems.

03-11-05, 08:10 AM
That dynamat project you described is essentially what we did with my car. Triple layer on every surface of the car. The floor, doors (inner and outer door sections), roof, firewall, trunk, fenders, etc. I haven't yet done the foam insulation because I wanted to use expanding foam that's designed for accoustics. Great stuff is more aimed toward construction and thermal insulation, so it's accoustic attentuation isn't as great. I also got in touch with the company that makes laminated side glass for most of the cars that have it, and I had some people there working on finding me laminated side glass for my car. I never got that finished though.


03-11-05, 04:55 PM
Well, after all that talk about the dynamat now I have to go and re-do half of it. A 95 year old buick driver drove right into the side of my DTS today and essentially destroyed both doors on the passenger side, and dented up both front and rear fenders. I'm in the process of dealing with his insurance company and I'm collecting the receipts for the dynamat work so don't end up with two un-insulated doors, making half the car noisy


03-11-05, 07:25 PM
Damn, that sucks. Good Luck with your repairs, I hope everything works out okay.

03-11-05, 09:53 PM
Well, after all that talk about the dynamat now I have to go and re-do half of it. A 95 year old buick driver drove right into the side of my DTS today and essentially destroyed both doors on the passenger side, and dented up both front and rear fenders. I'm in the process of dealing with his insurance company and I'm collecting the receipts for the dynamat work so don't end up with two un-insulated doors, making half the car noisy



Sorry to hear that man.... damn.

If you ever get the wind noise fugured out.. lemme know.

I hope you get her back on the road soon.

04-02-05, 02:30 AM
Anything doing, Scott?

04-02-05, 02:57 AM
I've been without my car since it got hit. Sad since I was planning to try to do some work on the car and we've had the good weather for it lately. I just got the initial apraisal of the damage yesterday. It took them three tries to get it appraised. (long story). Anyway, initial estimate is about 5000 dollars. Once they open it up they expect to find a bit more. I'm also getting an estimate for all the dynamat work to be re-done. I wish I had the car and I wish I had a bit more time because I'm really getting into the mood for exploring more mods for these cars. For a while I wasn't too concerned with power because of the traction issues but I've come to feel that on the highway it could certainly use a bit more. I'm also looking into the possibility of retrofitting the magnetic suspension from the STS. I've heard that there's a possiblility of a retro-fit kit for the vettes, and that suggests to me the possibility of one for a Deville. Another thing I've been thinking about is the possibility of simply altering the signal going to the adjustable shocks (for those Devilles with the variable damping system) to make them a couple steps harder of softer depending on driving circumstances. I haven't had the time to look into this too extensively, and with my car off the road I've been slightly less motivated. That's about all I've thought up recently. Anyone else here still interested in working toward more performance?

04-02-05, 05:03 AM
Well, I've always had big plans for my STS, I just haven't had the money. Between the higher stall torque converter, my plan to experiment with an extra set of exhaust manifolds, the possible addition of a higher flow cat, and maybe some lighweight mag aluminum wheel with some slicks (track use only), I juss haven't had the funds to get any of this done, or even started. I'm hoping to do the torque converter this summer, and find some descent rims and slicks for the track.

I'm also looking into the aluminum motor/tranny mounts, since they will hold up better with my driving style. I drive pretty fast, and harder than most ( I don't beat on the car though). The fluid filled rubber ones, simply aren't strong enough for the added stress of some of these mods. I'll get more vibration from the engine through the steering wheel, but I don't mind. It's just reminds me of the power, residing under the hood in front of me. :D

As you may have noticed, the majority of the mods I'm looking to get done, are geared more towards the transfer of power, instead of creating it. The northstar, is a difficult engine to modify, while still retaining it's driveability on the road. Anything is possible, but it has to work in the car. Sure you could build an 800hp northstar, but it's sure isn't gonna work while still in the car.

One thing, that I always wondered, was whether or not, you could get a chevy small block to bolt up to the 4T80E. I think that if someone found a way to stuff an LS6, or other LSx engine into the front of a northstar driven caddy, it would be pretty rediculous. While it might diminish slightly from the car's image as a whole (being that it no longe had the northstar), it would certainly take care of the aftermarket performance problem. Of course this couldn't be done on a street legal car so to speak, since it would be throwing codes left and right, provided you could find a way to start and run the other engine, while still allowing the rest of the cars electronics to function properly (damn near impossible I would imagine). It's just an idea I've been messing around with.

At some point, in the future I'll probably sell my Mustang, so I can start working on my sleeper project, which will be my real performance car. I'm planning on taking a late 80's early 90's 9C1 (police) Caprice, and swapping out the 350, for a Caddy 500c.i. engine. I'll then build up the tranny, and rear end. I'm gonna look for a 1970 500, so I don't have to buy the parts, to rebuild a later model, to the same specs. With the Edlebrock intake manifold, it should be just about the same weight as the 350, but with about 400hp, and 550 lb/ft of torque. That sort of power in a Caprice, will definitely suprise people. :sneaky:

In the mean time, I guess I'll try and get some of the mods listed above done to my STS, which I plan on keeping for a long time. My goal, is to make it into at least high 13's in the 1/4 mile. I thinks it's possible, but it's gonna take more time and money than I have at the moment. I'll start getting some of it done this summer.

04-02-05, 06:59 AM
Well, I've always had big plans for my STS, I just haven't had the money. Between the higher stall torque converter

I think a higher stall converter would make a big difference. I noticed my DTS bogs off the line - the stall isn't matched very well to the peak torque on the car. If you listen to the sounds on the Corsa website (the Launch) one you can hear it too.

I probably would never modify my car beyond the Corsa exhaust and possibly a K&N though. I want to set it apart a little from the geriatric crowd, but it doesn't need to be a drag car.


04-02-05, 03:49 PM
I did ask around alot, before I considered the idea. I spoke with one memeber on CaddyInfo, who had a 2800rpm stall converter installed in his 1999 STS. He said he didn;t experience any driveability proble, what so ever (lower mpg, more gas needed at stoplight,..ect). He also said, that with the Corsa, and a set of Slick, in conjunction with the higher stall converter, he ran a 14.1 in the 1/4 mile. So, even without the slick, it would definitely make an improvement.

I think that the sock one, has a stall speed of about 1200 rpm I think. With the way the power is ditributed throughout the RPM range in the northstar, it doesn't really start to move until about 2200-2500rpm I would say. I found this is most noticeable, if I gently press on the gas rfom a stop. The gar will slowly accelereate, but once it get's above 2500 rpm, it begins to take off.

04-02-05, 08:59 PM
I found this is most noticeable, if I gently press on the gas rfom a stop. The gar will slowly accelereate, but once it get's above 2500 rpm, it begins to take off.

Yeah I can feel the same thing. It wakes up at 2500-3000 RPM - even if you romp on it pretty hard (like floor it) you still have to wait to hit that sweet spot. If I ever have to rebuild the trans I would definitely put a different converter in it. But I wouldn't go through the hassle of taking it apart just to put a converter in it.

I have a 3600 RPM stall converter in my GN. It's perfectly fine for the street. It might be a little loose for daily use, but it's not terrible.


11-15-13, 12:35 PM
Hey guys, just finished reading through this thread. Some good stuff! I'm all about finding some MODs for my 03 DTS. This is actually my second, I had a 2000 for ab 3 years and it ended up just costing too much for major repairs and I couldn't dump any more cash into it. So I was in luck at the local dealer, had a DTS three years newer, pretty damn good condition, low miles and in Diamond White instead of the black i had before - which is a Godsend living in sunny florida.

I've got a problem w/ her at the moment, misfire in the cylinders so i'm changing out the plugs and boots hoping that its not a more serious problem.

But later down the road, I would love to get a cold air intake, and the exhaust. After that anymore upgrades would be great if I could afford and find them. I was reading before about a "road force alignment" and i'm wondering how much would that help milage/performance??

Also I'm coming up on 100k miles, about how much of a performance increase would I be getting w/ a standard tune up?

Good stuff tho on this thread.

11-15-13, 01:04 PM
But later down the road, I would love to get a cold air intake,Your car already has one from the factory, and it flows more air than the engine can use at WOT, at redline.

and the exhaust.There was ONE exhaust system available for the last gen Deville, a Corsa. You might be able to find one, it'll be ~$1,200-$1,600. I got 16 HP out of the Corsa system for the Seville.

After that anymore upgrades would be great if I could afford and find them.Other than brakes and tires, there aren't any.

I was reading before about a "road force alignment" and i'm wondering how much would that help milage/performance??A road force BALANCE is a method of balancing the tires. Nothing to do with performance or mileage.

Also I'm coming up on 100k miles, about how much of a performance increase would I be getting w/ a standard tune up?A "tuneup" on a Northstar is plugs and wires (or boots for '00+) by 100K. There will be no difference in performance unless the old plugs were causing a misfire.

11-15-13, 05:19 PM
You have what you have, and that's as good as it gets. The only thing a so-called "CAI" will do is lighten your wallet - same for cutesy boutique air filters and oil filters with nuts on the bottom.

If you carefully went through this thread you'll realize that the thread died in 2005 and at that time there were NO other engine modifications (worth anything but looks) except the CORSA, and now that's gone. Why ?? Because there is NO interest or aftermarket for this line of FWD Northstar cars. Yes, they're cheap - for what they were - in the used market but they're also ripe for hideous repair/maintenance costs. If a Seville or Deville is relatively problem free it's probably still in the original owner's garage. If it's a money pit, it's for sale - cheap - at the Korner Kar Korral.

Keep it clean, maintain it as new, and drive it like you stole it.

Look through my albums for the 2002 STS - been there, done that: ALL of it. Click my username, open the profile. left column, 2 albums, 6 pages of 2000 - 2004 Northstar stuff.

There are about (conservatively) 9.6 skrillion threads on Northstars and modifications in this site. Start lookin'.

11-17-13, 12:20 AM
I never saw the date on this thread lol, it was late and I was posting and searching for a few answers to help fix my current caddy dilema. But I did not realize a few of these things. There really isn't an aftermarket exhaust I can get for the car? a few more hp or mph would be great, and a little more sound would really make me smile more when hauling ass.

As for the Road Force Balance, when the car gets between 65-75 mph, there is excessive vibration and I would like to get that taken care of bc its pretty annyoing on the highway.

All in all i love this car, its my second. Had a 2000 for 2 years that was beaten to hell but still drove great. So if theres just mods for looks then i'll go that route i'm guessing in the end.

11-17-13, 10:11 AM
jd, If you have a specific question and a quick thread search in the proper forums doesn't turn up something, try to Google your question: "cadillac forums 2003 dts front end vibration" or whatever - always preceded by "cadillac forums .......... ".

You could ask a good exhaust shop how much it would cost to mandrel bend a s/s exhaust with 2.5" pipe and a decent pair of free-flowing mufflers and tips. The CORSA for your car was about $1250 +/- if you could find a left over assembly somewhere. Your 2003 DTS has the same engine/transmission setup as the same year STS, so find the Seville or Northstar thread titled "Vroom Vroom". There's a dyno run of a stock and CORSA system in there - the system is good for 16 hp just before WOT redline. Pictures of a STS CORSA system in my albums - the Community tab, Albums, the red Seville - 2 albums, 6 pages of stuff for your engine.

You should go way up ^^^ to the top black bar and study the entire Cadillac Technical Archive. Lots of good info you may not know.