FAQ: The Exhaust Thread

With the right cam it can sound good, but generally I agree it doesn't sound too hot when you open things up on a stock engine. Here's a few recordings to help you out. Mine's on page 4 of the thread:

https://rivperformance.editboard.com/t6854-exhaust-sound-clips

Okay I can live with that sound no gun shots were fired at the end thats awesome aa so what would you suggest?

I don't know the laws in LA for emissions. Check into that. If you can install a 3" downpipe and lose the cat conver, keeping everything else stock - it will have a nice low idle, some growl when you hit it, but no drone when cruising. That's how I like it. I've put my cat back on since that vid was taken, but it sure sounded good.

I wouldn't recommend headers for you at this point, but if you plan to mod the car some more they improve flow and will change the sound a bit - not for everybody - a bit louder up front and you can hear the valves more. Takes a little away from the soft luxury feel, but sounds meaner, more raw. I wrapped mine, which helps lower the noise. Hope this helps.

I have just begun putting in the work and its illegal here too so I want to go about it the right way .. I just want about close to 400horse and ill stop

Johnny5 wrote:

and ill stop

Thats what you say now...  

I want to keep the SC and bolt on a turbo im sure there are plentiful on mods needed for that major of a move .. but I just need economy for now with a boost lol..

I wish I had a good camera to take a new vid/sound clip of my Hooker Aerochambers.....he old vid I have on here is with those stupid DynoMax dual chambers. WAYYYY too loud they were.

I've always wanted some Corsa mufflers, but you can't buy JUST mufflers, can you?

EDIT: AND, I realized the other day that the O2 simulator I have in place of the CAT is useless considering I have the rear O2 codes set to "ignore"  

Silly question... Do muffles "break in"? When i had my exhaust put up, it sounded kind of raspy and was fairly loud, but i think it has a more mellow tone and is quieter now. I figured i just got used to it, but wasnt sure if mufflers actually do sound different after theyve been run for a while.

Sir Psycho Sexy wrote:

Silly question... Do muffles "break in"? When i had my exhaust put up, it sounded kind of raspy and was fairly loud, but i think it has a more mellow tone and is quieter now. I figured i just got used to it, but wasnt sure if mufflers actually do sound different after theyve been run for a while.

Absolutely. Mufflers will sound different after they "break in". Once the packing has heated/cooled a bunch of times, the real sound sets in. I have no clue behind the science of it all, but they definitely "break in".

Corsa sucks man they make them for the 02 and earlier Grand Prix but wont make them for our AA confirmed it as well I tried .... but I think im going to order the gtp stuff and have a shop mandrel bend the pieces for me so I could use them

AA wrote:

I don't know the laws in LA for emissions. Check into that. If you can install a 3" downpipe and lose the cat conver, keeping everything else stock - it will have a nice low idle, some growl when you hit it, but no drone when cruising. That's how I like it. I've put my cat back on since that vid was taken, but it sure sounded good.

I wouldn't recommend headers for you at this point, but if you plan to mod the car some more they improve flow and will change the sound a bit - not for everybody - a bit louder up front and you can hear the valves more. Takes a little away from the soft luxury feel, but sounds meaner, more raw. I wrapped mine, which helps lower the noise. Hope this helps.

Thanks man it helps alot when I know it sounds more expensive every time lol im going to start slow intercooler n exhaust thats and do you know of anyone selling a scanner ... im falling in like with this aeroforce but price is up up and away

Abaddon wrote:

Sir Psycho Sexy wrote:

Silly question... Do muffles "break in"? When i had my exhaust put up, it sounded kind of raspy and was fairly loud, but i think it has a more mellow tone and is quieter now. I figured i just got used to it, but wasnt sure if mufflers actually do sound different after theyve been run for a while.

Absolutely. Mufflers will sound different after they "break in". Once the packing has heated/cooled a bunch of times, the real sound sets in. I have no clue behind the science of it all, but they definitely "break in".

Cool. Im much happier with the sound of my exhaust now then when i put it on.

At some point I'd love to have stainless all the way from header to tail, but not have a loud system, especially at idle and low/mid RPM.

I wouldn't mind if it was a bit louder under throttle/WOT, but again not really obnoxious as I personally think that is counter to the look/purpose of the Riviera. But that's my preference of course

.... I think it is more interesting to have a true sleeper, quiet, refined.... but  


Jason posted quite a bit of info on different exhausts and their db earlier in this thread I think.... or one of the other threads on the subject. I think the Borla SS systems came in very quiet at idle.

al_roethlisberger wrote:

At some point I'd love to have stainless all the way from header to tail, but not have a loud system, especially at idle and low/mid RPM.

I wouldn't mind if it was a bit louder under throttle/WOT, but again not really obnoxious as I personally think that is counter to the look/purpose of the Riviera.  But that's my preference of course

.... I think it is more interesting to have a true sleeper, quiet, refined.... but    


Jason posted quite a bit of info on different exhausts and their db earlier in this thread I think.... or one of the other threads on the subject.  I think the Borla SS systems came in very quiet at idle.

He did but it didn't tell me wether or not he likes it cause it looks extremely loud on the phone and computer pictures lol but corsa go to there utube infomercial and listen to the V6 Camaro and V6 and Avenger they sound awesome from my ears but maybe we might disagree I like the sound out a 350z or a G37 factory

Johnny5 wrote:

al_roethlisberger wrote:

At some point I'd love to have stainless all the way from header to tail, but not have a loud system, especially at idle and low/mid RPM.

I wouldn't mind if it was a bit louder under throttle/WOT, but again not really obnoxious as I personally think that is counter to the look/purpose of the Riviera.  But that's my preference of course

.... I think it is more interesting to have a true sleeper, quiet, refined.... but    


Jason posted quite a bit of info on different exhausts and their db earlier in this thread I think.... or one of the other threads on the subject.  I think the Borla SS systems came in very quiet at idle.

He did but it didn't tell me wether or not he likes it cause it looks extremely loud on the phone and computer pictures lol but corsa go to there utube infomercial and listen to the V6 Camaro and V6 and Avenger they sound awesome from my ears but maybe we might disagree I like the sound out a 350z or a G37 factory

Here you go. He has some photos and a few videos with sound of the Corsa system installed:

https://rivperformance.editboard.com/t7775-corsa-exhaust

From page 2:

1) Cold startup and idle. Didn't warm up enough to drop idle down to 700. Stayed at 1k. http://video.cardomain.com/VideoPlayer.aspx?id=2385595
2) Driving around, windows and sunroof closed: http://video.cardomain.com/VideoPlayer.aspx?id=2385594
3) Driving with sunroof cracked open. Acceleration. http://video.cardomain.com/VideoPlayer.aspx?id=2385592


He later added some resonator inserts which he says made the exhaust a bit more quiet, but not sure how much.

Al

Im on my phone and it wouldn't let me hear the sound clips so I have to find some other way

albertj wrote:

denim wrote:

Albertj,
I like your reasoning, and the mostly stock approach. If I were to use your recommendations, that is, how you finally configured your own car, what might it cost, ballpark?

Short answer - You have to ask dealers for price quotes.  Because the PAU exhaust comes in one piece so shipping can be -- well -- interesting. That means expensive.  It could be as much as a grand or more to your door.  

Better (and cheaper) answer - PN of the PAU exhaust assembly  was 25749911.  This is *important* - it shows up in the GM system as a "converter" and lists for almost $810. A rookie parts counterperson is not going to get that it really is the *whole* exhaust and hangers - there's some goofiness involved like no picture in the system or some stuff.   Oh yeah you get $80 for return of your old cat.  

You should be able to get for less than $810 but you will have to ask around and negotiate.  You might want to check Monsterpartsonline.com and gmpartsdirect.com using the part number 25749911 and print those prices out and ask the parts counter person to come as close as he can to the pricing without an Act of Congress. I think dealer cost on it runs $350 to $450.  So the thing is an experienced parts counterperson with some discretion or a parts manager is not usually going to charge you a 100% markup for something like that.  I do not remember what I paid but it was less than the then-price for GMPD if you included shipping. And the dealer even had the lot attendant drive the thing to my house... it's all one piece and clumsy, we hadda tie a red flag to the part that hung out the tail of the S-10...

As you know the parts managers have some discretion.  So what you pay may depend a little on who you talk to at the respective dealers.  I am thinking they should come close to the GMPD price, if only because they don't actually have to pay shipping from GM.  Yeah, shipping is another matter.  GMPartsDirect wants almost $150 to ship the sucker.

I guess the point is if you can buy it from a dealer for less than $650 all-in for pickup at the dealer  you Found A Deal and might/should consider it.  

They will (may) want a "reason " for replacing the cat and assuming your mufflers are rusty you can just say "Preventive maintenance."  Which is what it is... unlike the aftermarket aluminized systems the factory system is T409 stainless. (you should clean it off with clean rags and alcohol and then paint it before install more on this below).  

So as I confessed before I earlier had a custom stainless exhaust fabricated and put on.  For that exhaust I bought and provided a new Walker cat (they have actually about the best aftermarket cats I don't care what magnaflow says) to weld onto the system.  When I sold the custom system I asked for and got my buddy's old cat as part of the trade (it was part clogged and the heat shield had rusted off the case). He sawed it off with a hacksaw.  I turned that in for my $80.- some weeks after getting the "converter" from GM.   And called it "preventive maintenance."

A little trivia - The new exhaust will come with an EmCon converter, which will be TINY and very close to the downpipe.    Don't wig out.  it is small because it uses a newer technology  "thinwall" substrate and flows better than stink (or any cat it replaces). It does not have to be big. Oh and you don't have to but I also fabricated an extension to the undercar heat shield out of sheet aluminum flashing (mill finish) and secured that with exhaust repair epoxy and I think pop rivets or teeny sheet metal screws I forget which. And in order to be sure I got my moneyworth out of the replacement I painted it (except the cat) with silver 'high heat' engine paint before install. It took weeks for the paint to cure (heh heh).  

A little more insight:  Have a buddy help you with the install, the one-piece exhaust is a bit much to get into place and does not look like it fits -- until it is all hung on the hangers, then it's great.  The mufflers just tuck inside the rear bumper skin.  They will scrape the skin going in but rest just above and inside it once it is all hung at the right height.   They are big. Getting it on, you pop the hangers off the new exhaust and swap them in for the old ones one by one in their respective places. Use the old ones as paperweights or some such or sell them.  The factory hangers are some sort of black miracle elastomer, I doubt they ever wear out.

When I did my install I (well I didn't do it keep reading) broke the center hanger, repaired it with same grade stainless bolts and used galvanized pipe nipples over the bolts for ferrules to go in the hangers.  Only reason was my bud (a very good manufacturing engineer by the way) mistook the swaged bolt in the hanger for a bolthead to turn (it happens) and busted it when we were removing the old system. I am responsible for my car so I say I broke the hanger...  Not a big deal, I am good at making once-and-done solutions out of common/odd hardware and the hanger can be easily copied form common hardware once done being peeved about breaking it.  

Apologies for quoting such an old post, but if I am reading this correctly, this sounds like an ideal solution for someone like me that would like a stainless exhaust, that probably flows plenty well for reaonable HP, and is quiet and an OEM fit.

From what I conclude from reading the description above, this appears to be the complete exhaust after the downpipe, including the cat, intermediate piping, mufflers and tips, correct?

So my questions would be:

1) What year PAUs was this available?
2) Was this the stock exaust for the PAU in those years, or an optional exhaust?

I seems to still be available at the various online GM parts sites (at least it will let me add it to my cart), but it might also be nice to know what year PAU this was available so one could keep an eye out at wrecking yards.

Thanks!
Al

Just got the exhaust checked out. No leaks found. I'm running ~1% rich. Would that do it? I still need to put the lining back in the trunk and see if that helps.

But why the heck am I getting exhaust in the cab? My back seat is out too so its open to the trunk.

Would any of this, no back seat and no trunk lining have something to do with the exhaust smell?

Is it possible a tune would help with this?
 

Im not positive but if its noticable after removing trunk liner and back seat, could it be a small leak in the EVAP system? Or would that certainly throw a code?? I think theres a definite difference between gas in the exhaust and actual gas smell. Is it strongest after filling up or anything like that?

And when the cars running rich, you can definitely smell it but its alot different smell than gasoline after it hits the Catalytic converter.

A tune IS NOT going to cure your problem. I'll give it a good look-over when you come up on Sunday.

I have no idea. I have no codes. It smells like exhaust. I have no cat.

I'm at a loss.

Would it have anything to do with the O2 sensor emulator Im using?

Abaddon wrote:

A tune IS NOT going to cure your problem. I'll give it a good look-over when you come up on Sunday.

Shoot. Thanks, Scott. Looking forward to the education.

You just had a cat delete. You're going to smell some un-catalyzed exhaust fumes with that.

~1% rich? How do you know this? LTFT?

Yes. LTFT.

When we cut the cat we found it hollowed out. So i dont think thats a factor.

AA is right. You are ABSOLUTELY going to smell "rich" exhaust with the CAT removed. It will make its way into the car sometimes, especially first thing in the morning and when you're backing up. Just wait until you smell mine......(ha, that's funny)

~1% rich isn't anything at all to be concerned about. I'm actually surprised it isn't higher than that. Usually slapping a pulley on and not tuning will gain you ~5% LTFT for the extra air.

Like I said, cat was non existent prior to DP install.
All the welds are good, no leaks.
Only difference is the O2 sensor emulator is now in place.

Could that be it?