I built a new subwoofer box today, 3/4" MDF.
60" wide X 18" deep X 14" tall. 6 cubic feet, ported with 3 4" X 11" PVC pipes. One layer of R13 fiberglass insulation along the bottom.
I was using 2 10" Rockford Fosgate HX2 subwoofers on a 40amp (500watts RMS) Kenwood amplifier. About a week ago on a whim I bought 2 12" Dual SD12 subwoofers from walmart to put in a box in the house hooked up to the stereo. They slam pretty hard for a $30 speaker!

So, I bought 2 more and took the 2 out of the house and put them in my truck. Shit bangs in the ported box with only 500 watts. I'd like to get a new amp for a full 700 watts RMS.
Nice build man and I love the wheels they look perfect on our obs trucks! Nice box too but, do you have it bolted on the humps in the cargo area and if not does it slide a little to the rear on fast take-offs?