Quote Originally Posted by petrified.rabbit
my exhaust pipe an flex piece under the engine are already flattened out from driving, not leaks yet, but i can not even think of trying more pipe under there, even oversized.

Xiogary's 4-1 header is 11 hp gain on the dyno with his car.
He also had the performance cams in and something else that most of us here dont have, actually he has quite a bit of parts we dont have. I think that him having the cams would boost his gains from a header, in my UNPROFESSIONAL opinon, and I could be wrong, but for those who do Xiaogarys header would not see gains as high as that, maybe 7-9 hp, which is still a considerable gain in the long run. I am by no means knocking Xiaogarys headers, but I felt that the differences should be ponted out for the comparison between the Aveos here in the US and Garys. Again, Im not a professional mechanic or racer so I could be wrong.