I have a 92 Mustang GT with the Ford Premium Sound System. When i got a new 4 channel amp i just ran RCA's from the deck to the amp and speaker wire off of the amp to the speakers. There are no Speaker wires coming off of the deck there for automaticly eliminating the factory amp. If you wanted to bypass the factory amp W/out an aftermarket amp just run new wire to the speakers off the deck. I had to take out the factory amp to i would have room for my wires off of my deck and EQ.