I know that the CRF450X is much faster than my XR650L or XL600. The CRF has that zone in it when you really grab a handful that is akin to going to warp speed. Just Crazy Fast! in fact that is my nickname for my new steed. Crazy Fast 4 fiddy. The old boys are heavier and older technology, strong runners, but no where in the ball park of Mr. 4 fiddy X.