I didn't have very good luck with any of the aftermarket primaries, they worked good at first but failed one way or another. When my qsc predator(gen1) wore out so quickly, I decided to upgrade to qsc raptor(gen2), well it snapped off at the inner hub within 50 miles. Ended up having to cut it off the crankshaft. Broke a spider in a stm primary and so on, they just don't last. I've been running a turbo primary and STM sec for a while now & no issues so far. I miss the lower ratio on take off with the aftermarket primaries but I have spent thousands on clutches that don't last.