I just finished installing one of QSC's clutch kits on my 550, and although I haven't had much of a chance to ride it anywhere other than around the yard and the road in front of my house a little bit, the difference is like night and day compared to stock. The first thing I noticed is that it doesn't engage so damn hard anymore, nice and smooth, perfect! That was one of my biggest complaints. From a dead stop, or even a slight crawl, a full throttle hit in two wheel drive is just stupid, just spins the tires in the dirt, 4 wheel drive isn't much different. On the pavement, it damn near pulls the front end and carries it like a muscle car until you let out of it! Top speed, at least from what I can tell (I'm not out to win a top end race) is still all there, I hit about 54 or so and it was still pulling. Support from Adam is stellar. He had no issues taking time to talk to me on at least three occasions, built a kit per my specific needs/wants, and answered all my questions without hesitation. Although I don't know what other guys kits are like, I would without a doubt, very highly recommend QSC to anyone. :top: