I built a new center console out of MDF, have an amp rack on the bottom with (3) amps (a Kenwood 250w mono, a Lightning Audio 1000w mono, and a Kenwood 40x4), a 1.5 farad cap, and distribution blocks. I have a custom ported box with about 2.4 cu ft housing two 10" Powerbass S-10 subs firing down, with about 1/2" clearance between the dustcaps and the amps at full stroke. The top of the box has cupholders built in, and has a lid covering a compartment large enough to hold about 50 CD cases.
I had two Celestion 15's in the rear quarterpanels running off the LA, and the two 10's running off the Kenwood.... fried one of the 15's , and am running the LA to the 10's now. The two 10's put out more than enough low-end, can't even see out the rearview mirror.
As I always carry tons of tools and supplies as a contractor, I have to be able to fold the rear seats down completely, and not have a box taking up ANY space in the cargo area.
Depending on if you can mount the amps under the seats, it is possible to fab up a center console box of almost 4.5 cu ft, and still have enough space for a pair of 12's to fire down at the floor, with a good 1" of clearance.