I'm trying to install aftermarket amplifiers in my Terrain. I have never been so aggravated trying to install a system. It seems they have created harnesses and plugs for every other GMC or Chevy model except this one. I have been researching for months with no luck. My truck has the 7" screen which controls the rear speakers, and the factory amplifier controls the front speakers. So running my 4channel amplifier to my factory harness to power the door speakers looks impossible. I have bought a full setup for this truck and can't install it without splicing and splitting wires or losing retention on certain functions. It's a nightmare I like the truck but hate the fact that it's so difficult to beautify the sound system to my liking. The only thing that I have done is upgrade my door speakers with Orion XTR's.