i have a 98 mustang, and its got a stereo with a seperate single cd player underneith it, i want to replace the speakers, and possibly put in an amp. first of all, is there a factory amp? and if so, can i replace it with a bigger amp to avoid putting in a new cd player and amp and having to run new wires? the stereo now can't even push the stock speakers at half volume continuously without it getting louder and softer. also, what would be a good setup to get? im on a budget of about $800