Rapter 660 would be nice, like an 03-04 maybe. But the yfz450 is the fastest bike. If you want to go newer with Honda, hte 450ex is a nice bike too. I have ridden a 400EX, and damn that thing flies... My friend has one, and he drag-raced his uncle on a Rapter 660, he said the Rapter would have won, but his uncle couldn't keep the front end down, and his 400EX won. His uncle hadto lay of the throttle a little on acceleration, and his Uncle weighs like 200lbs he told me... So if you are 16 and really small for your age, a 660 might be a bit much. But somewhere around 350-450 would be good. 250 would get slow pretty quick I think.