When the clutch chatters, put tranny in neutral, side step the clutch letting the pedal bang to the top.
That solved the issue with my Spec 2+. My Spec 2 clutch has never chattered in the 7000+ miles it's been in.
174,000+ miles, 5/20/12 new ej257 short block, 8/20/11 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. Also CHECK YOUR OIL, these cars use it.