99-2000 models had aluminum frames that were lighter but more prone to weakening under heavy stress conditions. If you are just riding you will be fine, but start doing wheelies, riding aggressive at MGVW and you will be stressing the frame. All I know is that the frames are weaker on these models but not to the point wear you need to worry about running out and getting a new frame and you will be fine w/ any aftermarket cans.