cat-back ???'s

[redlobster]

i dont have any forced induction or anything yet, not sure if i plan on getting any either, but i wanna get a cat back, what size would be my best bet for pipe? 2 1/4 or 2 1/2?
thanks for any help

[dukeplaya3169]

2 1/4 is what most people here have on their custom cat backs.
2 1/2 is great if you wanna run turbo/blower or high shot of n20
I have 2 1/2 on my N/A galant and felt a def. increase in performance through higher rpms..I haven't had any problems thus far...but if you don't plan on really getting serious with engine mods, just go 2 1/4.

[BEAST]

If you are asking for what size to get only for the cat back, just stay at 2 1/4. If you go 2 1/2 it will not make a difference because the rest of your stock exhaust is only 2 1/4. Either way it wouldn't make a difference unless you did your entire exhaust including new headers. Your exhaust is only as free flowing as your most restrictive spot.