Just a post about how I got the signals from my HU for my amp with high inputs. I went to the back of the HU and used posi-lock connectors at the harness. I then ran these lines from the front of the vehicle to the rear. From that point, I have control to go high into an amp, a DSP or a LOC. If ever I want to remove the equipment from my truck, I can just unscrew one side of the posi-lock connector and re-attach the existing wire.
While I do not like cutting into factory wiring, there is no harness available yet for our vehicles with a 8.4a/8.4an. I did research getting the connectors on my own and building my own harness, it is achievable but I would have to buy the connectors, the pins, a tool to crimp the pins, etc. and it was cost prohibitive.
Here is a pic of the result. Notice the heat shrink "nub" with the zip tie on it. Those are the existing wires that I could reconnect should I ever need.
I really like these posi-lock connectors. They are really strong, re-usable and make quite a nice connection. Look at the photo below how the wire forms around a conical pin, pretty nice connection.