From experience, what do you all think is the best cam and piston combo for MX? I would like to give my 400EX a good power increase for MX over the entire powerband. Also, any other rather cheap mods? Thanks.

 

What do you all think of an XR250 CDI box, XR400 cam, and a high compression piston? Would this cut reliability way down? About what would it cost? What kind of power increase could I expect with these mods? Also, with this CDI box, and cam, what brand and compression piston should I get? I don't want to have to run full race gas. Please help.