I Have Bass

Well, I thought you said it wasn't loud!
I misread what you wrote, I guess.

At any rate, firing them into the back wall is a good idea... you might even think about bonding an MDF panel to fire against.. get the old "compound loading" thing going, making sure the panel isn't absorbing any energy.

And no, there's no science behind the gains of "compound loading" as far as I know - I sure haven't been able to find any... but you only need to leave an inch or two in front of the subs.