they get pretty loud in a properly built ported box. the sq isn't the greatest but it is still good. mine were getting pretty loud with only 250 watts rms going to them. i have 2 12" punch hx2's i'm selling. they are the dual 4 ohm voice coils.
They are really loud subs with a bad sound quality. If you want to boom, they are perfect for you, but its hard to get linear response from them. I was going to upgrade to one, but once I modelled it, I'd have just been stuck with the awful peaking I had with my previous rockford. =\
