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1979 Coupe Deville, 1995 FWB & 6 Other Non-Cadillacs.
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759 Posts
Discussion Starter #1
I'm doing a dual exhaust conversion to my 78 FWB this week. I already got the 96 9C1 crossmember. I'm ditching the cat and resonator, it's just a question of which mufflers to get. I was thinking magnaflows because they flow good and they're not to loud. I'd like to hear from someone who has done this to chime in with an opinion.
 

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1992 Cadillac Brougham 5.7L
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78 Posts
ditching the cat and resonator will make it a bit louder, and magnaflow have a see-through dersign (unlike flowmaster's baffle system), which means much louder.....flowmasters are loud too....do you want loud in a cruiser? get rid or the cats and resonators, and just put new stock mufflers....u'll have more power/gas economy/flow by removing the cat, and ull keep the quiet yet present rumble of stock mufflers.
 

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1996 DeVille, 1985 Brougham SAGE GREEN!
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2,750 Posts
What all is involved in doing a dual exhaust conversion on a Brougham? The '78 and '80's are the same underneath right?
 

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1993 Fleetwood Brougham
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51 Posts
I like the sound of the Dynomax. Agreed Flowmasters are loud. However, I heard a Camaro 427 last Friday with Flowmasters, and it sounded great. The large pipes going into and out of the mufflers, probably 3 inchers, is what made the difference. There are many websites that have sound clips using various mufflers on different cars that you might find helpful. Just Google "muffler sound clips" and see what you come up with.
 

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Cadillac
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89 Posts
Invest in an X pipe. Not only will it improve flow but will eliminate the motorboat (forgive the pun) sound when decelerating.
 

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1996 DeVille, 1985 Brougham SAGE GREEN!
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Im impatient and i didnt get a timely response on my question. so i will post it again:

What all is involved in doing a dual exhaust conversion on a Brougham? The '78 and all of the '80's are the same underneath right? A rough idea on what this would cost as far a parts and labor. I want to help the mighty HT4100 breathe a little better,as long as its not too expensive.
 

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94 FWB, 93 SDV, 94 FWB (sold), 90 Brougham (sold)
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I like the sound of the Dynomax. Agreed Flowmasters are loud. However, I heard a Camaro 427 last Friday with Flowmasters, and it sounded great. The large pipes going into and out of the mufflers, probably 3 inchers, is what made the difference. There are many websites that have sound clips using various mufflers on different cars that you might find helpful. Just Google "muffler sound clips" and see what you come up with.
Dynomax would be my choice, especially for a '78. Dynomax seems to have the most "classic" exhuast sound. Flowmasters are too loud; they belong on a Camaro or Mustang, but not a Cadillac.

Im impatient and i didnt get a timely response on my question. so i will post it again:

What all is involved in doing a dual exhaust conversion on a Brougham? The '78 and all of the '80's are the same underneath right? A rough idea on what this would cost as far a parts and labor. I want to help the mighty HT4100 breathe a little better,as long as its not too expensive.
The '78 and the '80's are different underneath, different transmissions and crossmembers. Dual exhaust on a RWD 4100 would be a totally custom job, I've never heard of it before. You could go cheap, and just find a muffler with one input pipe and two output pipes, like DopeStar was considering a while ago, and just run another pipe over the axle, or you could go true-dual, like Destroyer did, and run both pipes side by side with the stock crossmember.

Brian
 

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1996 DeVille, 1985 Brougham SAGE GREEN!
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That is what i assumed. My good friends dad owns his own shop,and i think he could do a custom job for a reasonable price. Any suggestions on what would sound good/ give better performance muffler wise? I plan on deleting the cat and resonator as well. I dont want anything too loud either. The HT4100 can sound good,mine sounds pretty cool at idle( i have a small hole in my muffler.)
 

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1979 Coupe Deville, 1995 FWB & 6 Other Non-Cadillacs.
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759 Posts
Discussion Starter #9
So from what i gathered here i'm best off with the dynomax mufflers and running an x-pipe and ditching the resonator and cat. Should I run 2.5" or 3" pipes?
 

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1996 Fleetwood
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2,536 Posts
I'm the late guy chiming in, but another one to consider, if any are still out there, is Ravin from Midas. They have 3 main types, mild, moderate and loud as f***. I have midrange on my Fleetwood, and the deeper growl is very nice to hear. Midas discontinued them a little while back, but you can still find some out there.
Clip here. Mufflers and a welded in H pipe on this car.
http://www.youtube.com/watch?v=SQls_AIUZ28
 

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1979 Coupe Deville
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414 Posts
I'm sure this is a touchy subject, but I wouldn't rule out a cat/converter(s). From what I understand, some of the better high-performance converters don't rob horsepower and can actually decrease unwanted backpressure, resulting in small horsepower gains. Plus, they burn off all those bad gases.

I'm no expert on exhaust systems though, so don't flame me on what I just posted. That was the general consensus on the Firebird/Camaro boards I use to frequent (owned a 91 Trans Am convertible). In any case, when I do a custom exhaust on my 79 CDV, I'm gonna use a cat/s in the system.
 

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94 Fleetwood Brougham
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7,534 Posts
Read this first before you dump $$ on an exhaust: http://www.pontiacstreetperformance.com/psp/exhaust.html

There is no GOOD backpressure..... BUT, always be aware of backpressure referenced EGR valves can hose up some EGR timing, causing some pinging issues.... I just swapped mine to a ported EGR, or design out EGR if you can...
 

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94 Fleetwood Brougham
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7,534 Posts
But it does require at least a cam like the LT4 cam (the 1996 LT4, not the 1970's LT4 which is a 400 with 180hp....), which isn't gonna be happy with a tight stall converter and lethargic gearing like most Cadillacs have....
 
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