Alright guys, I need to know if this is a good idea or not. The only way I can see myself fitting a 10 or even a 12" subwoofer into my Car is to make a downfire box. I'll be using a SSA Dcon. My question is: How far does the Speaker have to be away from the floor, and do I seal 3 sides as in bring all 3 sides down to the floor but leave one up to try and direct the sound pressure rearwards almost like a port? I have 10.5" Height, 23" Width, and 18" Depth to work with. I'm planning on keeping this a sealed enclosure of .9ft after the .10ft displacement. Can someone please help? If there is a problem with down firing a subwoofer what is it?