Almost every 600 has had some kind of refresh after 2 years- 99-00R6 changed in 01-02 with the new tail section and minor engine upgrades, 03-04 ZX636, and here's the new 05- http://www.2wf.com/articles/top_sto...B26BFEF37EC.asp which is completely different. It seems after 2000 the bikes need to be upgraded faster than before- remember how long the F3 was around? The GSXR 600 SRAD-97-2000, kawi zx6r 98-02 (mild body upgrade in 2000). So many people are buying these things when they are first released that the companies feel the need to continue changing them in any way they can.