[lair12]

Looking at thebmwofsouthatlanta site which lists all part numbers, it seems to indicate that there is only one wiring harness for all X3 F25 models.

This would imply that the rear D-pillar speakers wire are already there and that the harness connection for the 12 speaker 205W system is the same as for the 16 speaker 600 watt dsp upgraded system. Is the harness connection the same??

Could I just buy the 600 watt amp and drop it in my vehicle? Will the existing harness directly connect and be fully functioning? What would it take (if possible) to then get the equalization on the head unit display?

I've bought new upgraded front speakers, so I could buy the d-pillar mounts and trim pieces and drop my front speakers in there. I count nine twisted pairs going into the harness, which suggests that the wires for the rear would indeed be in D-pillar. Would this give me a fully functioning 16 speaker system?