3” or 2”1/2 Exhaust

805gn

Member
Joined
Dec 27, 2007
What size Exhaust you guys running 3” or 2”1/2 a street car just bolt ones looking for a kit ready to buy ?
 
Pypes makes a 2.5” and a 3” system, both of 409 stainless steel. Guys have found the Race Pro mufflers to have less drone. The mufflers mount ahead of the rear axle.

GN1 Performance has a similar 3” polished 304 stainless steel that is a copy of the old ATR Pitbull system available from several vendors

RJC Racing has a stock style setup that’s 3” single in to dual 3” out.

It seems even the 2.5” systems will run in the 10’s.

It just comes down to your preference.
 
Pypes makes a 2.5” and a 3” system, both of 409 stainless steel. Guys have found the Race Pro mufflers to have less drone. The mufflers mount ahead of the rear axle.

GN1 Performance has a similar 3” polished 304 stainless steel that is a copy of the old ATR Pitbull system available from several vendors

RJC Racing has a stock style setup that’s 3” single in to dual 3” out.

It seems even the 2.5” systems will run in the 10’s.

It just comes down to your preference.
All are great systems. Personally, I have the ATR 3" crossflow with the passenger side outlet plugged at the muffler and that pipe removed. Running just the driver side pipe. I had some clearance issues with the RideTech suspension that required a temporary work-around that has turned more permanent, lol. Can't tell any difference in power. Number one on that list for me would be the RJC racing unit. Jason's customer service and build quality is awesome
 
IMHO the backpressure that the engine sees is from the turbo, and that's considerable!
From 1 1/2 to over twice the boost pressure!
The turbo spools due to the difference in pressure from turbine inlet to outlet.
The lower backpressure after the turbo will probably allow quicker initial spooling. .
Is it measurable? Yes.
Is it relevant to overall H.P.?
Yes, prolly only measurable on the dragstrip though.
Sound and bragging rights are prolly the biggest issues for most of us.
Let your ears, wallet, and ego decide!
Me? I've got dual 3".
I got a great deal on it!
New combo isn't finished yet.
Don't know how it will run, or sound.
But, I'VE GOT DUAL 3" ON MINE!
MR.Spool can fill in the rest!
TIMINATOR
 
GN-1 3" dual on my current GN Legend.
I ran 3" Torque Technology (long since gone the way of the dodo) duals way back in the day on my 1st T-Type RUQWKNF.
I ran an ATR 3" single on my White Limited RARE T.
And a Pypes 2.5" dual system was on my Blue T Sarah when I bought the car. I never got around to upgrading it to 3" dual.
The others are correct. Sound plays a huge difference between all the different systems out there. I personally have always liked the dual 3" sound the best. And Mr.Spool is correct with his question. How fast do you want to go?
What I've seen is, once you reach that 550 flywheel hp range, it's best to consider larger diameter piping on these cars. IE going from 2.5" to 3".
Can a car make 700 flywheel hp with just 2.5" exhaust? Sure, but the engine might not be the happiest doing it.
Over the years, there have been numerous sound clip videos made on these cars. Most have been lost or deleted online.
I made one myself in 2018 after installing my 3" GN-1 exhaust system on Legend. You can check it out here.


In the end, it really boils down to what you like, especially if this is a pump gas, no alky stock engine bolt on street car.
Some single exhaust systems have drone while cruising, others don't. I know the 3" single shot ATR system that I had on my white Limited years ago, actually made me a tad queezy when I drove it from Central Mississippi to Bowling Green KY in "98, because the drone was so bad at highway speeds. Given, that was a 8 hour drive depending on traffic. YMMV.
Don't forget, the header system you choose to run will also greatly affect the sound and the performance/transient response/spool up too.
Hope some of this helps.

- Patrick
 
A well designed dual 2.5" system will not hold you back even to a high nine second car . I have a ATR dual 2.5" with pitbull mufflers like Scooby . Dual 2.5" pipes are 40% bigger in area than a single 3" , so with a 3" down pipe the "restriction" is right at the turbo .
My car with ATR dual 2.5" & 3" downpipe @ 30 psi boost .
 
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