Some people have had great results with them, others hate them. For the price, you can't really pass it up. I'm going to use one when I have to change out the clutch on the 125.
i tried the tusk clutch. first moto it would swell up then cool with 1/2 a lap......it would go from full on with no lever pulled, to not working at all with the lever pulled...within just a few corners. it was scary.
next moto it swelled up on the gate, the bike rolled forward into the gate and stalled right there.
on monday i sent it back...complete waste of time and a days racing.