Here goes:

My current setup includes a Single 12" Polk Subwoofer powered by the second channel of my amp in bridged mode. The Sub currently sits in a q-logic custom fit enclosure. As it stands the specs for the speaker and the box work perfectly (i.e. speaker calls for .85 cubic feet, enclosure volume is .85 cubic feet.)

Recently I found this MTX Thunderforms enclosure at Crutchfield. Now normally I'd move right past this item were it not for the two 10" Polk GNX subs I have that were part of my previous vehicle's installation (their enclosure wouldn't fit in the truck. ) I ran these two bridged and in parallel and to be honest they sounded amazing!

The specs of the MTX enclosure are 1.77 cubic feet. My 10" subs call for .66 each (1.32 cubic feet.) Would the fact that this enclosure is a little bigger ruin the sound? I like the idea of getting a little more room from the back but don't want to sacrafice empeg/audio quality to get it.