Update^ There is definitely more back pressure with this catback. If there was a power loss I don't think it is enough to make a difference but the butt dyno feels different. When I shift now it picks up with less gas where as the invidia needed a lot of more effort in picking up in between shifts when coming off the clutch.. Not sure if this will be bad or good for performance but they say you don't want any back pressure. Doesn't feel bad though I kind of like it. I do want the most out of my set up though so will see how it does next time one of the V8 guys try to race me...