Hello, I am planning on installing a 5 channel amp into my 97 gmc sierra. I have 4 pioneer door speakers, and a 12" sub, I plan on using rca cables to work all speakers and sub from the amp to an aftermarket stereo. I am also replacing all speaker wire so I can run it to the amp. Would I still need to use the factory harness for anything besides power wires? I plan on doing the install this week or this Wish me luck!