I have 2 18" btls with 2 AQ3500s. and i want to build a "wall" in the back of my ranger for them. the room i have is about 36" high 15" deep and 48" wide. Im not looking for someone to design it for me. i want to learn and understand how the ports work. I see that its there slot or aero port. and i was going to do a slot port towards the top with the subs at the bottom. im using the cal. that torres made and i dont understand what the woofer displacement or brace displacement means. i know i probably got myself in way over my head if i want it tuned to anything but now i have to learn and this seems like a awesome place to learn. Thanks for any help.