OK here's a question for you guys with engineering degrees. I've owned an '04, '06. and '09 YZ450F. None seemed to have the kind of torque that my '99 YZ400 had. Why would a smaller displacement engine seem to have more bottom end power? The other thing I noticed is that all the 450's have the popping on deceleration even with rejetting. The 400 never did. Don't get me wrong, the 450's are better in the handling department than the 400 ever was but I do miss the tractor like power.