Yep used a set on an 09 800 and they ripped hard from 4000ft to 10,000ft plus that I used it at. SLP twins with a Carl's package...runs great! Have to run some race gas and follow their clutching spec's to get the most out of them. I also varied the amount of race gas based on elevation for consistancy in performance. Took a little experience and expiramentation since I rode at a lot of different altitudes and conditions throughout the season. Their setup was best for 5000-8000 which is their home stomping grounds. DO IT...very cool!