I put a MSC stage 1 kit in my 21 600T. Hated how "buzzy" and high revving the bike was overall. Honestly, I was expecting a bit more improvement after all the hype I heard about it. Seems to just lower the clutch engagement slightly for smoother takeoff but honestly I don't notice much else. Haven't ridden enough to notice any MPG loss. Part of me wants to get the helix (would essentially make it the stock tire performance kit) as well but with that comes the added expense of the compression tool, clutch holder, etc and I'm not sure if it'll be worth the cost