RE: clutch
Stock XRAY Alu shoes with hard springs - for the XRAY
KHZ Alu with 1.0 Kyosho springs - for the SP2
Racers Edge Carbon and 1.0mm Kyosho springs - also for SP2
The XRAY shoes lasts 2 gallons easy with some maintenance. Not sure about the KHZ ones yet.
The carbons I only use for 1 gallon or so.