If I don't plan to do a turbo upgrade on a GSR and I am happy with the sound of the stock CBE, will just a downpipe or testpipe make just as much power as a full TBE? I want to get the most bang for the buck and if I don't have to spend $1200 on a TBE that would help out a lot.
I know that for STi's, you could just get a downpipe and tune. This would yield just about the same power as a full TBE and tune. Does the same thing apply to the X?

 

i would think that keeping the stock cbe would increase backpressure which would limit some hp in the end....

 

As I understand it, and i'm just a newbie so I may be wrong, the largest gains come from the test pipe and CBE on the X and the stock downpipe flows well enough that your money is probably better spent elsewhere.

 

Sorry for the newb question. What is the difference between a test pipe and a downpipe? Does the test pipe go in between the DP and CBE? Is there a link to a diagram somewhere?

 

You wont gain anything, the restrictive cat-back will limit the flow of exhaust gasses.

 

Yes, the exhaust gases flow through the turbo/wastegate into the O2 housing, then downpipe, then test pipe/cat pipe, then cat back.

 

The Test Pipe over the stock cat is likely the biggest restriction followed by the Catback exhaust where mainly the muffler is the next most restrictive. The O2 Downpipe area is likely the last thing that would help power and only really helps with higher flow and larger turbo setups.

That said you usually want to upgrade the last part in the chain for best results working your way from the farthest from the engine to the closest. Balancing intake mods with exhaust mods also helps balance things as well. I would be willing to bet that on a stock turbo replacing the O2 downpipe on an otherwise bone stock car would likely yield almost no HP gains.

 

Alright I'll contribute my newb question to this thread as well, what's the difference between a regular down pipe and the o2 downpipe?

 

Not a noob question at all, infact thats a great question.

Regular downpipe replaces 1 piece, and that is the downpipe. An 02 downpipe is a great piece as it replaces both the downpipe and the 02 housing which in stock form is an incredibly restrictive piece. A decent down pipe is around $300-$450, while the 02 Downpipe is ~$350. By itself the 02 housing is ~$150, so if you do some simple math its a great idea to buy a combo downpipe/02 housing.

 

the stock exhaust is 2.x inch.
most of the aftermarket test pipes are 3"
if you are planing to delete the cat and install just a test pipe maybe is better to find someting with the same diameter that the stock exhaust,
a 3" pipe is going to create a bottle neck right at the end of the test pipe, and build up some nasty residues at the bottom.
maybe i'm too **** with my car. it's just my 2 cents

 

nah I agree with you man.

 

yess it gives the most gains for a simple bolt on with a tune

 

Has anyone done a back to back test from stock exhaust to just a 3in dp and no cat?