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
166WHP/147TQ Running Rich at flat 12! More power to come once finished!