My friend and I both have KFX 400's. Almost exactly the same. We both have Dyno Jet kits. K&N filters rate on the carb's, and the same sprockets. He has a Yoshi pipe and header, while I have the FMF power Core 4 with the HI-flow header. He seem's tp pull away in a long drag around High second through third. In 4th and fith we are at an even speed. He ends up being 3 quads ahead? I thing its not the pipe difference, but jetting. Does any of you know or have some suggestions. Oh ya I almost left out that we both installed #150 jets from the kit. I was thinking about going to #155. Its my opinion that in 2nd I rev out to fast while he's pullin away.????[img]i/expressions/face-icon-small-blush.gif[/img]