That box is way too small for 12 12's. I just saw the stereo shop down the street from my house had a van w/ 12 12's in it, each sub had about a 1cuft. volume. before displacement, with kicker cvr's. so running about .7 cuft. per sub (not enough). They had a 4000 watt amp (cant remember what kind) so about 300 watts to each sub.Now, do you seriously believe more is better, when you can put two square kicker 15's in there (or whatever) and blow the pants off whoever is in that van?
I pulled up (91 honda accord 2 door) with my two 12's on 2400 watts (weak) and still blasted em out