A friend and me just built a ported enclosure for his 2 P. Miller 12s. Jmac designed the box. He is running a Punch Power bd1000a (500W @ 4ohms) to power the subs. The subs get loud and rattle the heck out of his little Nissan Extended cab truck. It would be hard for me to judge the sq of the subs as at high volumes I just here the rattle of his truck. Tickles your butt, feel it in your chest and little tingle in the nose.
I would probably agree that they are not the cleanest sounding sub, but they defiantly get loud. I'll post pics later tonight hopefully. He paid $69.99 a 12 locally.