mine also chatters, it's a spec stage 1. I took it out and it looks like there's a ring on the middle of the contact area of the clutch, and that's where it has been rubbing. i wonder if it's a bad flywheel or if it's just the clutch. I'm going to call spec and try to get a refund, i was thinking maybe a ram clutch.
The TOB on my Stage 1 squeaks too and has since it was installed at the end of this summer (it's not my daily driver so I've put less than 1000 miles on it). It was installed by a mechanic who knows what he's doing too. Had I known, I would have bought a Ford TOB instead.