i agree w/ blackmagik, one 15'' will give you more shakes, rattles and and squeaks then 2 12''s. I have 2 12''s now and one day for kicks a friend hooked his 15'' up to my amp (after unhooking the 12s) and the 15 was rediculous. unless youre competing or desire boomy bass rather than crisp more-accurate bass, stick with the 12's