Aero ports are your friend. 10-12 cubes with aero's tuned in the lower to mid 30's would be pretty loud. You could even keep your same equipment.Its 4 15" Powerbass C subs. (400 rms each)Powered with a Kicker SX1250.1 amp (1500rms at 1 ohm).
In the recomended sealed encloser. I could build a new box tuned to like ... 35hz but Ive yet to deal with building a ported box with all of the subs in the same chamber.