I'm planning on boosting my car but it prob won't be for a while so I can gather parts and stuff. I know that I want to get the RS*R Exmag exhaust system now because my current exhaust is just getting loud and annoying to me. I could buy this exhaust in 2.5" or 3" piping (for turbo). If I go ahead and buy the 3" one now would it be ok until I got around to boosting? Or would it be ok if I got the 2.5" one and then boosted with that one on, would it make that much of a difference? Please help.

 

3" is way too large for an N/A motor. 2.5" should be fine for both N/A and turbo depending on your goals.