Vacuum leak on your clutch....? How many miles on your car? When was the clutch replaced? What Flywheel do you have, but like in any manual car rattling/chatter will be your Retaining Bearing and Slave Cylinder one piece unit in the SVT, Alum FW will chatter also, but that normal for lightweight fw
CM Stage 3, Alum FW, HawkPS Brake Pads, EBC Rotors, Torsen Differential, Tom's Tune, Rear Tranny Mount, FRSTS, Lunch Box Delete, MSD Coilpack, Massive Wires, Massive Strut Tower, TS Mani, TB, Cam tuning, and Cat Cam.