If you are looking at Tyga body work the 21 will fit on your 18 with a little trimming. I have Tyga body work on my mc18 with a mc21 radiator and i had to trim around the radiator. Also i have rear sets and BIG FEET) and needed to trim lower to fit around the shift lever and rear brake lever. Tyga body work comes with new upper mounts and the body work is not drilled so it's easier to fit.
