OK, now those of you who have the factory radio in the car and have done this - want to take it to another level?
After doing this mod, then click below and do two things:

1) Replace the head with a real four channel head (make it a marine head and it will match the interior).
2) Do the four channel mod in the link below.

NOW you have the door speakers working correctly, AND you have control over the rear speakers.

Here is the four channel mod:
https://www.crossfireforum.org/forum...-channels.html