If you got an adjacent garage you want to build out into anyways forget about a commercial sub. Infinite baffle.
http://home.comcast.net/~klone-audio...-12Shiva1.html
There was a great forum dedicated to these, but it seems to be down right now. The above link will get the idea across though. For the cost of a B4 you could buy a ridiculous amount of these (and therefore even more output capability):
http://www.partsexpress.com/pe/showd...number=295-455
and a good quality pro amp. Do some searching in the DIY area for infinite baffle or IB subs. You'll get lots off good info on this and discover that no one who has built one regrets it and almost no one has willingly gone back to a regular sub after having one.
Also as the poster above noted, the design of any of the SVS box subs pretty much makes in wall placement impossible. I also wouldn't recommend it.