Help with installing 2002 Mustang

Hi guys, This might sound like a newbie question but please bear with me, Im used to installing on import vehicles, I dont know that much about American cars. I plan to install a Pioneer 8600MP and a system on a 2002 ford mustang and I was wondering about the internal amps- i want to add two MTX amps to power the subs and the speakers, what do i do with the internal amps, do i just pull all the wires out and just leave the internal amps hanging like that or do i have to do something to it.....and where do i connect the wire for the power antenna to the pioneer head unit....thanks in advance....

go ahead and use the constant, acc, ant turn-on and ground on the stock harness. leave the factory amp and just bypass it by not hooking up any of the speaker wires from your pioneer (make sure and cap off the ends). if you are gonna run 2 amps then you need 2 sets of RCAs (one for sub, one for mids/highs). then wire the door and dash speakers from there. not sure about impedence on stock ford amplified speakers but im sure someone here knows right off hand. if you replace the speakers with aftermarket then you wont have to worry about that.