You DO know that you can get a lot more out of your subs if you stack them together? Subs are usually non-directional, so they can be either side of the stage or together, and it won't make much difference except within a few feet of them. But there's a thing called the 'coupling effect', where, if they are stacked on top or side by side, touching, the overall volume level from them is greater than if they were apart.

I know some bands run their subs in the MIDDLE of the stage (on the dance floor) side by side, and run their top cabs on poles out to the edges. Then, they put a monitor or something on it, (no point wasting extra stage room!) for the singer, and they get a VERY solid thump on the dance floor with less gear than you would expect...

Anyway, look into the 'coupling effect'. It's how things like the Bose get to sound so good.... little speakers, all stacked close to each other.