I have one (RFP-1212) 12" Rockford Fosgate Punch DVC 2x4 ohm subwoofer in a sealed box filled with polyfill that is a little smaller than the recommended enclosure size. It's one of their older models, but all the specs are archived in this pdf: http://www.rockfordfosgate.com...n.pdf
400 watts RMS
800 watts Peak
I actually had that particular subwoofer connected to a RF Punch 75.2 amplifier , it was bridged at 2 ohms and worked for many years, but it took a crap recently so I replaced all the wiring and amplifier with something new. It ran pretty hot at 2 ohms, it would overheat sometimes during moderate length trips on hot days.
For that amp the specs are
37.5 x 2 @ 4 ohms
75 x 2 @ 2 ohms
150 bridged @ 4 ohms
I figured this new amplifier would be better matched with the subwoofer (closer to 400 watts RMS @ 8 ohms) , but I didn't check that the 560 watts of the power acoustik was at 2 ohms. I just assumed 4 ohms. . . and you know what assuming does.