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Exhaust Modifications.

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02BlueGTP

New member
Hey guys, my first post! I have finalized most of my supporting mods for my pulley due anytime now.. however, my concern is with my exhaust. I was initially going to remove my u-bend, but once i got underthere, I decided to lop it all off. Straigh pipe all the way back to the factory y pipe to the mufflers and stock tips. With out my Cat (not illegal where i reside) and resonator, i notice the sound to be nice at idle but up top and between shifts it sounds like @#$Y^. And did i just blow all my back pressure out the window?


list of mods done.

180 t-stat
TB spacer
MSD wires
k&N cai
straight pipe

things still to go on

3.4 pulley
DHP or ZZP or Overkill cpu Still not sure which one
love to hear differences and feedback from cpu owners too.. Thanks a tonne!
 


A) without a cat and resonator it will sound raspy and junky. these cars make a foul exhaust note, no matter what you do to the exhaust.

B) backpressure doesnt matter on a roots blower car, so dont worry about it.

C) you need more than that stuff to get that pulley on. you need some exhaust mods (the catback does absolutely nothing for performance, so that doesnt count) to help with the flow you just created with a smaller pulley. i suggest getting headers as they are pretty cheap nowadays.

D) get a DHP or an overkill. ZZP is known to have crappy PCMs around here
 
i used a 2.5" pipe from my 3" dp to the y, same mods as you plus a plog. even w an intense pcm i got 3* kr, so i pulled it off and am getting a 3.5 mps. good luck to u,,,,,,,,get an aeroforce gauge if u dont already:th_thumbsup-wink:
 


98SilvermistGTP said:
You do not need headers to run a 3.4.
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Really. I wish I was as smart as you...:th_winking:

Get the headers now that way you won't have to worry about it in the future.

If you don't have the money for the headers then get a PowerLog, 3" Downpipe/U-Bend Delete. Save the pulley for last and get that PCM on before it...IMO.
 
In any boosted car (turbo or supercharged) you want the exhaust as free flowing as possible! Im sure the stock mufflers wont flow well. And yes the grand prix will sound really "raspy" without resonators. Maybe look into a full 3" exhaust (more flow the better! And will support more with future mods) a high flow cat and big resonator(s) to some straight through mufflers.

No point wasting money on 2.5" exhaust and wishing you went 3" down the road (then spend more $$$)

Just my 2cents.
 


because the catback does not do anything for performance. there are plenty of guys making 350+ whp on a stock catback.

a 3" catback just makes it loud and wastes money. now a 3" downpipe, that is needed. anything past that is just fine at 2.5".
 
SilverGT said:
In any boosted car (turbo or supercharged) you want the exhaust as free flowing as possible! Im sure the stock mufflers wont flow well. And yes the grand prix will sound really "raspy" without resonators. Maybe look into a full 3" exhaust (more flow the better! And will support more with future mods) a high flow cat and big resonator(s) to some straight through mufflers.

No point wasting money on 2.5" exhaust and wishing you went 3" down the road (then spend more $$$)

Just my 2cents.
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Ha. Like Bio says the stock catback flows very well. Hell some dyno runs even show a LOSS of power with a aftermarket catback system. Only time you would need anything like that is if you are running some huge trim turbo setup where 3" is a necessity.

Bio248 said:
catback does nothing. a 3" is a waste of money.
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It just looks good and sounds like poop:cool:

SilverGT said:
How exactly is 3" a waste of money? Care to elaborate?
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See my post above ;)

Bio248 said:
because the catback does not do anything for performance. there are plenty of guys making 350+ whp on a stock catback.

a 3" catback just makes it loud and wastes money. now a 3" downpipe, that is needed. anything past that is just fine at 2.5".
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X2.
 
The bigger the exhaust, the better it flows... The better it flows, the more power you make. Simple.

And sorry, I was meaning a full 3" exhaust (including downpipe). Yes a 3" catback would be a waste.
 
My last comment was about boosted cars.

Even though Ive seen RSX's make more HP with a 3" exhaust vs a 2.5" exhaust. It was N/A and he still made a bit more power (10-12whp and torque).
 


what is the point of spending 500+ $$ on a catback that MAY pick up a few horses??? you could buy headers with that and pick up way more power.

the stock cat back flows fine.
 
SilverGT said:
My last comment was about boosted cars.

Even though Ive seen RSX's make more HP with a 3" exhaust vs a 2.5" exhaust. It was N/A and he still made a bit more power (10-12whp and torque).
Click to expand...

Dyno sheets on a 12 WHEEL HORSEPOWER GAIN on a 4 n/a 4 banger...maybe to the crank LOL

Stick with the stock catback. When I installed my 3" System (First big mod after CAI, T-Stat, and plugs) I straightpiped the entire thing and it was just A LOT louder and nope...no faster. Put in a 3" Downpipe/U-Bend Delete...WOW!! Seat in the pants difference.
 
SilverGT said:
The bigger the exhaust, the better it flows... The better it flows, the more power you make. Simple.

And sorry, I was meaning a full 3" exhaust (including downpipe). Yes a 3" catback would be a waste.
Click to expand...

Um, no, it is about velocity, if bigger was better, we would have 3" primary headers, and 5" cat backs, the stock cat back flows fine, on our local 600+HP whippled 3800, it ran with a stock catback for a little while, now a 3" is on there, unless you are making more than 350WHP, you might as well just burn the money.......


and the Dyno gain on the RSX, peak horsepower isn't what it is all about, sure the car could have gained 12hp at the top, but what about the losses in the middle and the bottom, I'd bet the average HP was lower......
 
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