Are these nice subs??...they are 400w rms and 700w peak...dual 4 ohm...double stacked 100oz magnet...not sure on xmax...need 1.75 cubes each ported...will 3 of them do the job in a 7 cube ported box with 270w rms to each???...i hear they are SQ subs...but are they loud??...Will the be able to be in the mid 140's db??..thanks for the help