[hootb18]

if you dont get the future mods and stick with 2.5 yes you will be hindering your performance, in the fact that you would have gained more with 2.25. the pulses in the exhaust system need to be pulled out. the tail of each pulse helps to pull the front of the next one. this is how a properly sized exhaut system works. if it is too large for the hp application the pulses will bounce around and not pull each other out, thus creating backpressure.