I say run really good 6.5" speakers in the doors, 6.5" or 6x9's in the rear and run it directly off the head unit... take most of the lows/bass out of them... turn your highs all the way up, treble a notch or two down from that and fade the sound to about 60% rear and then run a single 10" sub through a mild wattage amp.
you will VERY surprised on how well it will sound.. .and you wont distort anything!
this can be done fairly cheap.
I have a Kenwood Deck, Sony xPlod 6.5's front and rear, JBL 400w 2ch amp pushing a 750w 10" Lightning Audio and a 700w 12" Kenwood.
just my $.02
