i currently am running 1 12" id max on 750 watts at 2 ohm, the sub is in a 2.7 cubic foot box tuned at 30 hz. i also have a 15" ported box thats 4.5 cubic feet tuned at 34 hz. if i want something louder than my 1 id max can you guys suggest a 12" or 15" that i can fit in either box. also my amp does 750 watts rms at 2 ohm and 1500 rms at 1ohm, and i can have a box built if needed, i want to try and spend 450 or under on the sub