I've only spent a year beating on one and the only problems we started to have were the axles snapping (around the 20psi range and 4-5k launches) when launched hard constantly. I think at one point we had the flywheel bolts grind and rip off but that was about it. He got custom axles made and replaced the clutch and fly with some company and no problems since! From the first day of modding it, the car read 45k and I believe it was a 00 or 01 B5 body biturbo S4...

I'm trying to get one eventually