I need a box designed for 4 American Bass XFL 12s. The box will be going in a 99 Suburban. Subs will be powered by two Sundown 1500s. I have two 6 inch aero ports that I can use if they provide enough/not too much port area. If those won't work, I can slot port, or buy different aeros, but I'd like to keep the cost down. I want the box tuned to around 35Hz. Box size is 45 wide, 26 tall, and you can adjust the depth as needed. I'd like to save as much room as possible, so I'd like the size to be on the small side of the recommended air space. I want the subs to fire back and the ports up if possible....maybe side would work too, but not much clearance there. I'm not sure what box design cost, but I'm willing to pay a fair, reasonable price.