Originally Posted by b3freak

First of all, we need to determine which stock system was factory installed in the car and what was changed by the previous owner.

Porsche made three common system configurations for these cars:
1. 4 chan/8 speaker "base" system
2. "HIFI System" - 6 chan/10 speaker system (added a 6 ch frunk amp and door subs)
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[img]webkit-fake-url://493e2715-49dd-49d1-9de2-51cd7804489c/imagejpeg[/img]
3. BOSE System - 6 chan/12 speaker system (BOSE processsing, amp, speakers, subs)

Take some pictures and we'll be glad to help. These OEM systems run low impedance and so mating the old with the new may produce unwanted results.