What would cause my top end to be flat? I have the dg exhaust, +4 degree advance, 14t front sprocket, p&p, high compression, new topend with weisco piston. Good low end, hard hitting mid but the top just goes flat. Any suggestions? I'm running 290 main jet. stock pilot jet and needle jet is set in 3rd groove from bottom. thanks. If you need anymore info just ask.