AdamOj

I'm trying to get a new radio harness for my car but I'm confused on what to get, the person who wired up the stereo before me used both the blue plug and the white one (pic below) but from what I've seen on ebay they only need the white plug, will the stock amp and sub still work with only the white plug connected?

Ebay harness: http://m.ebay.com/itm/280758939852?nav=SEARCH

m1k3yg

You have two options, you can run the speaker wires from the new head unit to the trunk. That's where the speaker wires come from. The stock head unit only puts out a signal and then goes through the amplifier and then the speakers.
Or
Run your own wires from the head unit to the doors. Just tap power from the blue plug. There may be a way to power up the stock amp to drive the sub since the sub output on head units is just a signal

AdamOj

I should have reworded that lol will this harness for the SC work on my GS?