I am kinda at odds with whether to go with a 2.25" exhaust pipe or 2.5" pipe on my B13 SE-R. I would like some help in this matter, so any advice would be welcomed. The engine in the car is a USDM SR20DE but I am thinking to change to a JDM SR20DE engine, not sure yet. Oh,by the way what is the difference between JDM and the USDM SR20DE? MY engine has 145,000 miles on it. How much longer does anyone think it will last me?