i run 2 rl-p 12's sealed off a nine.1. right now its not getting enough voltage, i just have a single 4 gauge wire going to the back, split into 2 8 gauge wires, so the amp definitely doesnt have enough power yet.
my box is about 2.9 cuft without the subs, 2.6 with them, so 1.3 per sub. i put about 4 pounds of polyfill in the box. it is in a hatchback, so thats part of the reason, but it pounds, and sounds very nice doing it. it flexes my roof a little bit, jumps my vision, doesnt stop you from breathing but it makes you work at it a little. i parked it earlier and left it on, walked away from it just to see how far it could be heard, i got about 200 feet away to the side, and could still hear the bass clearly. if i play something like late night tip, or a bass cd, my rear view mirror will fall down every minute or less, and its not loose or anything.
so yeah, rl-ps can get nasty loud sealed. im almost scared to imagine what they would do in my car ported, but ported boxes are really hard to make for ***** ams.