DWPC

I want to replace the PCM in my 06 CTT with an up-to-date head unit. I'd really like to have a simple block or interconnect diagram of the system to see what connects to what, and where the components are buried. Being in the boonies, the installers in my area have never seen a Cayenne. One installer told me that the entire system, including all the speakers, have to be junked and replaced because of MOST complications and Bose speaker impedance.