You said you wanted them firing forward...in most SUV's without a wall, they will sound better, and deeper firing at the rear of the vehicle. It gives the waves more room to extend. I would give them about 1.5-2 cubes sealed. They sound better in bigger boxes from my experience. I heard a couple of them in a pretty nice size ported box, probably 2.5-3 cubes per sub and they pounded pretty hard. You have plenty of space and if you're taking the seat out anyway I recommend porting them. Good luck.
Dad, Electrical Engineer, MBA
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