I have a 00 YZ, just got it last weekend and did a 2 hour mx yesterday but the track was more like a short cross country, with laps no longer than 8 mins but not what i would call a motocross track. The bike ran great, only problem i would say is that i wasnt ready for 2 hous of racing, and that it wasnt hooking up the way im used to, havent raced for 3 months and coming off a RMX 250 and still getting used to the bike, but a heavier flywheel maybe the answer to it, but awesome power everywhere else and like i said getting used to the bike is the main problem, and havent raced for so long. As for it compared to a 99 i wouldnt know, my RMX was a 94 and the difference is amazing, the YZ is SO much better in all departments.