That may be true. I'm actually in the process of rebuilding my motor. You mentioned that you did not see an increase in power with "performance parts" and I don't doubt that at all. Every engine is different, even identical models. I did a lot of reading around the net and in some 4x4 magazines about Toyota performance and the general concensus I gathered was that a header and 2-1/4" exhaust gave a noticable increase in power felt when climbing hills and accelerating and such. The same goes for cams, but I haven't read much on big bore throttle bodies, so ya got me there.