I'm running a 15" Solobaric L5 and it hits hard. I have a Kole Audio 1440 watt amp pushing it. I have it wired up parallel. I used to have a Hifonics Brutus amp putting 700rms watts to the L5 and it was almost too much. The Kole Audio amp is pushing prolly 500rms watts and it has some solid deep bass. The Solobaric line is great for some ground pounding deep bass but they aren't great for SQ as some other members have mentioned.
What kind of box do you have your sub in? I'm running mine in a ported box tuned to like 135hz or something close to that. It is a perfect box for that type of subwoofer. I tried a sealed box setup for awhile and it tightened up the bass response some but really took away the lower frequencies.