Never mind. I've just found out that the only real problems were with amps. Fibre optic was only used from the amp to the stereo, so if you only had speakers and no amp, then there isn't any fibre optic cables to worry about. I just need an adapter to turn the Porsche plug into a standard ISO plug to fit an after market radio.
Which is this: lhttps://www.ebay.co.uk/ulk/itm/400659879734
You can delete the thread if you like guys, or leave it to help someone else
