Metra Wiring Harness
 

Good Evening,

I just received my new Kenwood HU (DDX-616) and the Metra Wiring Harness and antenna adapter.
Well the wiring harness has a black wire, which is thicker than the rest, but it has a tag that says "FOR SUBARU ONLY." I am sure this is the correct harness after double checking and seeing some pictures.

My question is, is this the ground wire?

Also in one of the pictures i saw that black wire is spliced for a mechanical connection to a ground. Is that correct/necessary?

Thanks for your help, this is my fist time doing any kind of electronic work on a car, and I wouldn't be able/feel comfortable doing it without all the great help from this site.

Cut it and on the head unit harness ground that black wire to a solid part of metal on the car. There are 4 bolts around the shifter lossen one and put it under that. Yes you can make the wire longer.

Thank you.
One more questions. I also got the polk MM6501, if I use the radio to power them (until I get the pdx-5) should I run new wire or use the stock wire? If I use the stock wire how do i connect the crossovers?