i have a 04 400ex i am in the process of putting a xr400 piston in the wheeler. i have a fmf powercore4 slip-on with a stock header. i put pro taper bars on it and jetted it. And i am willing to listen to anyone who had advice on building the best woods wheeler. i figured that the 400 is a good base and i want to build up from there. so if anyone has any ideas or advice i would be more then happy to listen. the 4-stroke world is new to me i grew up on the 2-strokes, so anyone willing to give me advice would be a big help. thanks