what size downpipe?

i wanna get a downpipe for my gtp.should i go 2.5 or 3"? in the near future ill be dropping to a 3.4 pulley,will the 2.5 be sufficient or should i go 3".within the next year ill be getting a intercooler and dropping even more,so whats gonna help me most now and later to,thanks for any help.

I'm pretty sure the GP's come with 2.5" exhaust, so unless you plan on replacing the whole exhaust system to 3"...go with the 2.5" it should be sufficient for the 3.4 pulley.

I'm pretty sure the GP's come with 2.5" exhaust

More like 2 1/4" (2.25"). Also, the stock downpipe is double walled meaning it is two pipes in one. The inner pipe diameter is around 2.0".

Interesting thing is, I ordered a 2.5" DP from ZZP, and when it came I measured it and it seemed to be closer to 3" than 2.5"....?????

I'm not a fan of aftermarket downpipes. Limited by other exhaust components, flow and backpressure. Exhaust manifolds, CAT converter, resonator, mufflers and the size of the rest of the exhaust plumbing. What good is it with a 2.5" or 3.0" downpipe when the rest of the exhaust is 2.25".

The bottom line is nothing beats headers. Although more expensive the most noticeable bang for the buck. :grinyes: