89 Mustang Speaker Advise

[pk222]

hey guys was hoping you could help me with my setup. i have an 89 mustang hatchback and just got a pioneer deh-p5900 reciever installed. i have 2 4in kickers in the dash, 2 kicker tweeters right above my head, 2 polk 6.5s in the doors and 2 polk 6/9s in the rear, when i first got this it sounded good but didnt have a lot of output. i tuned it for a while and it sounds a little better now but it doesnt seem like it would keep up with the sub i want to put in my car, i want to get a single 12 inch fi q and power it with eather a hifonics amp or if i can wait get probably a us amps md1. the guy who owned the car before me told me that he had an amp hooked up to power the speakers, so when i had the reciever installed none of the wires were ran. i know the polk speakers suck and im planing on changing them soon. what are your guys opinion on what i should get for speakers and if i would have to power them with an amp to get the sound equal. and would the amp give the speakers more output or more clarity? im sorry this is probably a really stupid question but ive never tried hooking an amp up to regular speakers. thanks in advance everyone

[pk222]

bump, please guys i live in the major country and have no one to ask for help