Have a look into engine mounts or the pitch stop mount. Even the gearbox mount. If there is something moving when the pedal is released it may cause a clunk.
The only other things I can think of, and don't quote me on this, are:
- Oil Seal Leaking - It is possible there is oil on the clutch from a leaking rear main seal. Was this replaced when the clutch was done?
- Clutch hydraulic fluid needs replaced? Air in the system? Or Master/Slave Cylinder has an issue. Try bleeding it. I would recommend an air bleeder. I was left carless when trying to bleed it traditionally.
- Clutch pedal needs adjustment? Where is the pressure/friction point? I had all sorts of issues with mine when I had a new slave cylinder installed. Wasn't bled properly and the clutch would be soft/non-existent when cold and almost at the top of the pedal travel when hot.
- Misaligned pressure plate? Was the clutch aligned using an alignment tool?
- Any shuddering when taking off? Was the flywheel machined?
- Is your flywheel single mass or dual mass? If it is dual mass and wasn't replaced and you have installed an Exedy HD, it might be causing issues.
This article here is very informative. Have a read and see if you have those symtoms.
http://www.aa1car.com/library/2004/bf40459.htmHope this helps