It all depends on what you are looking for, and how much you want to spend. My buddy put a Bombadier 670 engine in a Polaris XC 400. We also replaced the entire front suspension with aluminum. We replaced the rear with a M-10. We had Jaws make pipes to fit the Bombadier to a Polaris body, and put a digitron racepack to keep track of temps. Everything on the extertiror looks stock (except for the suspensions). What a fun , fast sled that gets attention wherever you ride it. That was about 7 years ago, when the Pol-Bomb was born.