Well about 20k miles ago installed an ACT HD 6 puck on stock cmc. I have never launched the car, but i am an agressive driver. On friday, it blew... popped like a frozen soda. I had purchased the magnus kit at the same time as the clutch for "just in case". i never opened the box till SAT. i was missing the bracket to lock the clutch pedal ball. I called MAgnus and told them and they shipped out one directly. So i guess the ACT clutch just takes longer but does destroy it, not break. when i took mine out, it came out in 3 seperate peices..... not cracked, but seperate. housing broke in two and the inner plastic shaft. Should be up and running again soon as soon as i get the missing piece.

 

ive had my act act hd 6 puck clutch kit for 30k miles and my stock cmc is still running strong.

 

i would say just have one "just in case".... after it went there were a few things that i really didnt put together till it went. if you start stalling in first that is not normal.... it is starting. better to have one and not need it than need and not have. ( reduces down time)... the ACT is definatly more cmc friendly than the exedy twins.