Just thought id add some of my experiences to this thread. Had my Car tuned by C&V a long time ago now. RWKW was limited due to valve springs. After a couple of years I return and had the upgraded valve springs added. and ended up with close to 260RWKW. With the extra power I was spinning the wheels to much under power, so for more traction I put some new wheels on my car. I am running Yoko Advan 275's on the rear. So tight a fit that I had to remove plastic lugs holding wires on the inside of the wheel wells. About a month after I put the weels on. Planetarys went. This is running a edit that slams the gears to the point that you think that a hammer is being used to change em. been running on new gearbox now for over a year and no problems, on the same tune. Was told that the planetarys are just weak in some of these boxes so its a bit of pot luck as to how much power they can take before they go bang bang. Wayne