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Discussion Starter #1
So I threw the CEL for P0420 (bad left cat). Since the cats are part of the system, replacing it is stupid expensive. So I'm considering some full exhaust options while I'm down there.

I've checked out some videos, but the variation in video quality makes it though to compare my options. Whats generally considered the quietest options? Preferably without any drones at static speeds.

Another option I'm considering is just cutting out both cats and welding in some electronic cut-outs. Any suggestions towards avoiding further CELs due to the EGT jump without the cats?
 

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2006 STS-V and 2007 STS-V The Murdalac
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Stock is the quietest exhaust you can have. I'd leave it alone if you are concerned about noise and drone.

The only way to avoid a cel if you gut the cats is to have the codes turned off with a tune.
 

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Discussion Starter #3
Thanks Timmy. Your input holds a lot of weight.

However, I've always wanted an exhaust, so it was most definitely bound to happen. Just wanting something more than stock, but still the tamest option.

One of our few options should be quieter than the others, right? Or is it not a significant difference? I may just go cut outs to have the option on the fly.
 

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Discussion Starter #5
That's not a half bad idea either. Most definitely the cheapest too. I'll googlefu some results from that. Thanks.
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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Corsa does a lot of work designing their systems with extremely low/no drone. Not sure what's available for the STS-V, bit for many applications they offer different levels of aggressiveness/volume.
 

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Maybe swap out the stock res with an x-pipe and keep stock mufflers?
That would be my suggestion if you have to change something on the exhaust.

Another option if you are going to replace the manifolds is headers with stock exhaust. This is my favorite, and not just because I make the headers. There are no cats in my headers so you'd still need to tune out the cat codes.
 

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Discussion Starter #9
so you'd still need to tune out the cat codes.
Any input on how id do this? Do you reflash or anything I can pay for to get this resolved? I'm not too privy with my local tuner options here in Montgomery AL.
 

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2017xts vsport platinum, 2011EXT, gt500
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Personal experience is corsa don't drone. Had them on a 2010Shelby and they were perfect
 

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Any input on how id do this? Do you reflash or anything I can pay for to get this resolved? I'm not too privy with my local tuner options here in Montgomery AL.
I can flash cars but I can't do it remotely. You'll need someone local or your own hptuners software.
 

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'06 STS-V, '17 CTS-V
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TimmyC headers & a full Borla exhaust on mine. No drone whatsoever. Prior to Tim's headers, the Borla sounded just a little less tame than stock. Perfect for a performance sedan.

If you buy the exhaust and feel you have drone, call Borla, and they'll send you two inserts for FREE to hammer into the tailpipe prior to the muffler that restrict the pipe ID to 2" from 2.5". I called and had them send a pair to me due to others here complaining of drone, but never needed them, either before or after header installation.

I can tell you that they are loud when you stand on it and civil when you're not. When I'm not messing around, I can't even hear them I the car.
 

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08 STS4 V8 1SG & 04 SRX4 V8 & 01 Monte SS
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TimmyC headers & a full Borla exhaust on mine. No drone whatsoever. Prior to Tim's headers, the Borla sounded just a little less tame than stock. Perfect for a performance sedan.

If you buy the exhaust and feel you have drone, call Borla, and they'll send you two inserts for FREE to hammer into the tailpipe prior to the muffler that restrict the pipe ID to 2" from 2.5". I called and had them send a pair to me due to others here complaining of drone, but never needed them, either before or after header installation.

I can tell you that they are loud when you stand on it and civil when you're not. When I'm not messing around, I can't even hear them I the car.
In my non V with GMPP Borla I asked about the inserts when I ordered the exhaust. They charge like $50 each and they said there was like 8 places they could go .... So YMMV. However I've not noticed any drone in the year I've had the exhaust.
 

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In my non V with GMPP Borla I asked about the inserts when I ordered the exhaust. They charge like $50 each and they said there was like 8 places they could go .... So YMMV. However I've not noticed any drone in the year I've had the exhaust.
Nope. Just called them up, forwarded a copy of my receipt to their customer service guy to prove my purchase, and they sent the parts free of charge. You can put them anywhere you'd like in the setup, and that'd mean anywhere prior to the mufflers-I didn't say "just before the mufflers."

As an FYI, I told the a Borla Customer Service Rep that I had already installed their system, and that due to drone I needed these "venturis".
 

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Discussion Starter #15
I can flash cars but I can't do it remotely. You'll need someone local or your own hptuners software.
Is the HP Tuner needed to hold the tune? Or can you use it to set the tune and disconnect after? Basically, should I put an HP Tuner on my todo list? Just a typical intake, exhaust maybe pulley sort of setup.
 

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Is the HP Tuner needed to hold the tune? Or can you use it to set the tune and disconnect after? Basically, should I put an HP Tuner on my todo list? Just a typical intake, exhaust maybe pulley sort of setup.
It's a software and cable setup that allows you to edit the tune and flash it back on the car. It is not permanently installed and you can flash the car as many times as you want.
 

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Discussion Starter #17
It's a software and cable setup that allows you to edit the tune and flash it back on the car. It is not permanently installed and you can flash the car as many times as you want.
Thanks, but do I need it to hold the tune though? Can I get it tuned with it then resell it? Or is this piggy back going to be permanent, provided I want these CELs gone?
 

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Discussion Starter #19
You can sell it
Ah if that's the case, you wouldn't be interested in me shipping you (and paying you for) an extra ECU to tune? I know you said you don't do it remotely, just curious why. I suppose it's a bit riskier when you tune for theoretical and hope it applies in production.
 

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Mine has Magnaflow and I have some drone. What is odd is that the drone is "limited" to the driver seat. 1st time I had the wife drive both of us noticed it. She asked why does it sound for loud did you change something? At the same time I was thinking wow this sounds nice and quiet in the passenger seat.. It Def dos drone a little for the driver though

Exterior wise they have a nice mellow rumble at idle, but very reserved otherwise. Pretty cool as it does not stand out, but does rattle the side windows in the house.. I reved at work messing with a buddy and he said all he heard was the blower (Spectre1&2 intake)..
 
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