[KevinH1990]

The answer to your question about returning to the OEM head unit depends on how the previous owner installed the aftermarket unit. If he used a wiring harness adapter, it will be fairly easy. If he or she cut out the original connectors and spliced in the new unit, it will be much more difficult.

Unless the car originally came with the cd changer, there will be no wiring for one. Porsche seems to make a different wiring harness for each car which supports only the options installed at the factory. I've noticed that Japanese cars (at least the ones I've owned) seem to have the same harness in each car and it is much easier to add options later.