I'm considering doing a custom built setup for my subs in my car. The port here would be behind the armrest in the back seat. When the rest is down, you'd be able to look back and see the speakers. And since I haven't got hosting and images on here down yet, prepare for text drawing.

hahaha
___ ___
\_{_}_/
____________| |____________
| \ / |
| \* */ |
| \* */ |
| \* */ |
| \ ~~~ / |
-----------------------------------
The * mark where the face of the subs would be.
At the ~~~ I planned on putting a design of some sort on the inside of the box, so when someone looked back, they'd see it. The entire setup would be taller than the gap the armrest hides, so some sort of lighting would be done from the ceiling of the box to illuminate it all. My thought was a Cadillac Emblem where the ~~~ are, and a black light might look good. But, I'd like to know what people's theories on it's sound would be like. I don't do astounding amounts of power, and want a clear, crisp sound in the lower volumes. Friction thinks this setup may create an audiopass which would give me high volume and hard hit, but both at high levels. Any other theories?