We put one on an '02 Summit. Took some time to tune it in but it ran really strong. Then on about the 5th ride, it stuck a piston... 4 corner seize, middle of the day.
New pistons and running again. Ran great for another 4-5 rides, then same thing, 4 corner seize.
At that point we traded off for a stock top end.
We were running it with the non-hooded needle jets... I would not do that. I think that may have been our issue... those needle jets/carbs sucked.
But as for power, noticeably stronger than stock and the guys at RKT were super helpful and got us parts fast to fix it. The guy that owned it just didn't want to mess with it any more after the second seize.
sled_guy