I too would like to know if anyone out there is having success with the aftermarket clutch kits for this sled. Thus far I have not heard of many good experiences, hence I have started tuning on my own. Started with a set of Heavy Hitters, an AC yellow / white spring and stock secondary set-up. (55/53 red/white spring) engages smooth at about 4000rpm, HUGE improvement in acceleration, (seat of pants) and good top speed - no time to verify actual numbers. It appears to overrev just a bit, I have a 59/53 helix and a green snopro spring I plan to try, but unfortunately the little snow we had is gone, and local lakes are questionable, postponing further testing.
IMpatiently waiting for snow in MN