I might be wrong, but one of my old Baja500 buds said the KX-500 had more than enough horses to go 100mph, but the desert makes you pay a huge penalty if you stuff the front end at that speed. He came in top 5 at least 3 years.
Believe it or not, I'm starting to almost run on the tennis courts! After Sept. '07, I hadn't run more than 3 steps due to the ankle problem, but my body adapted, albeit slowly, and I can actually run for wide balls and overheads that land within 2' of the baseline.
It's weird though, I can now get there, but I have to learn to setup the feet all over again, making this current evolution of LeeD by far the most clumsy...