I have my wr timed to yz specs and love the top end power, however i would love to get some more mid/low power without loosing the top. With my old 4 strokes, i would always add a highcompression piston and a cam, and maby bore it. My question is with the 400, what is stock compression, and can i run a higher compression piston with pump gas? would an aftermarkert cam set like a hotcam, etc really make a difference in power? Do they make a big bore for an older 400 like mine?Is it possible to swap in a newer 450 cyl? thanks alot guys....been riding the bike stock and love it, but always looking for more power....ive been riding with streetbikes lol.