back in highschool i had 2 ma audio hard kore 12s one behind each side of the seat and then ported snail shell box that vented through the arm rest hole. Hit 148 db on the dash with 10,000 watt ma audio amp running 2200 rms to each sub and .5 ohm mono! oh and 2 marine batteries where the spare was, god i miss that system way over kill tho. My next set up will be 2 sound splinter 8's in the 6x9 locations walled off to the strut towers and vented through the arm rest should be around 1 cubic foot each side and not burn up too much space.