I'm trying to see if there is a way to cut the wires from the factory amp and install an aftermarket amp to the door speakers without routing wires from each door all the way to the back? If it is possible, what are the color codes? Thanks in advance.

 

Word.

LF Speaker (+) BLUE/GREEN AT RADIO HARNESS
LF Speaker (-) GRAY/BLACK AT RADIO HARNESS

RF Speaker (+) RED/GREEN AT RADIO HARNESS
RF Speaker (-) BROWN/BLACK AT RADIO HARNESS

The factory amp for your front and rear speakers is the deck. You can cut these wires at the decks BLUE harness. The cut wires on the car side run straight to the speakers. Use the cut wires coming out of the deck to run to your amps input.