04 Grizzly 660 - I bought this kit and had my dealer install it while some other work was being done. The top end was screaming powerful, but there was a huge dead zone in the bottom end that made it stall. You might get lucky if you have some different components, I was running a penland pro exhuast and K&N filter. They ended up having to adjust it to get it to run everywhere in the band, now it feels pretty much like it did before the kit. I am pretty disappointed.