I have a 12 L7 Dual 2 Ohm model in a Subzone Ported Box. I HAD a Hifonics NX750 hooked up to it until an internal error in it screwed me over. I had 750 RMS @ 1 Ohm hooked up to the sub.
Extremely loud sub, very clean. I here so many people degrading the L7's sound quality but it is just so untrue.
The more power you put into this sub the cleaner it will be i guarantee you.
This sub takes about 2 weeks just to break in the rubber because it is so thick. The L7 seems to be very well made and constructed and it is one heavy SOB. I bought mine off of Crutchfield, I cant remember if i paid 350 or 450, it was somewhere in between there. The L7's can be found a heck of a lot cheaper at websites such as acaraudio.com. You can get one for a cheaper price than acaraudio.com on ebay, but you won't be getting a warranty.
Overall the L7 gets extremely loud and would sound excellent in both ported and sealed boxs and it does get very low.
Overall I would give the L7 a 4.5 out of 5 only because their is no perfect sub out on the market today......except for maybe a W7 ;*)
And for all those who want to impress their friends, 2 of these in a sealed truck box will set off car alarms, trust me i know!!!!!