I was building a few boxes messing with my btl's I built 1 box that was 5 cubes with a 60 square inch port (minimum enclosure rec) and a box that is 9.6 cubes with 105 square inch port (close to max rec size) I ran 1500 watts to each just messin around and in the smaller box the sub didnt hardly move, however in the huge box 1500 watts actually pounds really hard oh ya both boxes are tuned to approx 38 hz I never knew it made that big of a difference in the enclosure size.