Clutch Masters Hydraulic Flow Control Valve.
The extreme performance demands required of today's performance cars coupled with an aggressive clutch can cause extreme driveline shock loads. The Clutch Masters FCV-2000 (flow control valve) will help reduce shock loads by allowing the clutch to slip slightly during engagement. This is accomplished by controlling the return flow of the hydraulic fluid. This device will not restrict flow during disengagement and as such, under normal driving conditions the pedal release and engagement will not feel different.
This valve goes inline with your master and slave cylinder, and it has several different size inserts with different orifices, to let you fine tune the clutch engagement. If you side-step the clutch, it will just barely slow the engagement to decrease shock load on the drivetrain. If you use the smaller inserts, it can be fine tuned for drag racing type use.

Driftmotion recommends this item with twin, triple or quad disc clutches. Since it allows a little bit of slippage, the clutch needs to be rated at a higher torque capacity than the engine produces.