I hate to confuse the OP even more, but take a look into the Fi Audio Q series driver. I finally had a chance to hear these drivers a few days ago, buddy of mine has 3 15s in an explorer each sub had about 3 cubes of airspace and the box was tuned to 28 hz, also each had it's own Mtx amp, forget the exact model but IIRC was about 1k watts rms per driver.
Anywho, they get loud, stupid loud, they can take a beating and they sounded great doing it. He played a bit of rap and some rock, w/ the 28hz tuning it pounded out the low notes on the rap songs, and also kept up very well on the double kicks on the rock songs I listened to.
Also, for what it's worth, Fi Audio is owned and operated by the same person that designed all the drivers for RE Audio.