well i had the 15" SX on 900 watts and it was nice then i upgraded to an 18" havoc on 1200 watts but i was choking it in my trunk since the box was only 5 and a half cubes and the minimum was 6 so i sold it i had 400 dollars and couldn't think of anything that could get loud with only 1500 watts and 400 dollars and 5 cubic feet they need 1.25 cubic feet each so it works out perfect i was gonna buy a 15" MT but it wouldnt be loud enough on only 1500 watts