Hi there,

As far as "supercharger problems" the only one I'm aware of is that the Bosch intercooler pump tends to die an early death, which in turn disables the supercharger. Basically, the car goes into "limp mode" under these circumstances until the faulty pump is replaced.

Oil leaks are generally around the valve covers if memory serves, which is resolved with new gaskets.

Another common problem is that the automatic transmissions leak from faulty O-rings in the electrical connector.

All of these problems are fairly cheap and easy to resolve. In general these power-trains are very reliable once the few nuisance issues are corrected.