I have the 2.5" megan single, maybe looking to trade for the slightly louder and bigger Inidia N1. My buddy has it and i noticed its allot louder witch i dont mind but i would rather have the 3". I raced him with my exaust on and his off. I beat him (he has AP2 i have AP1) after about 105mph, i started to pull pretty hard. So there are gains. Just never dynoed. If your interested let me know we can have a date to switch and help get out exausts off =D. Going turbo later on so the 3" will help, i didnt think about it till a bit back