To start, my bike is a '06 YZ450F, JE 12.8:1, full exhaust, Wood intake, and PR2 built head (porting very close to stock). I'm still looking for more top end power, typical '06 with power falling off after 8500-9000 rpms, but an animal before that. If I could get the power to extend farther (not necessarily more peak power) without loosing the brutal power before that i'd be happy. I just picked up USED web camshafts grind #963, their top-performance cams for supermoto and flattrack racing (I am racing flattrack), but still have to buy correct valve springs before installing. They claim a modest increase in HP in upper rpms, but i'm worried about valvetrain reliability and loosing low end. Another option I have been looking at is getting the carb bored (2mm over), which I have heard great things about, and does not affect reliability aside from the slight stress more power would put on the engine. The carb mods would be alot cheaper, cheap enough that I could pick up another used carb to send out and have the option of switching carbs if needed. What limits the YZ head from making power farther? Are the cams a waste without changing porting? Is the stock carb bore choking power at high rpms? Is the ignition not aggressive enough at high rpms? I'm leaning towards boring the carb now, but i'd greatly appreciate any input on either method of HP. Thanks in advance!