99-01 - 16 bit processor,external fuel pump
99-00 - unrestricted after 186 mph ands other can be to with a TRE.
02-up - 32 bit processor,fuel pump internal
03 up - better starter system,clutch cushion from the factory,gold forks and calipers
01-up - steel subframe
05-up - Flash-to-pass headlight button,Headlight cuts off when starter is engaged
Otherwise pretty much the same.