I had two 15" x.x.x. with 1200 rms each. One sub alone, hooked up correctly, with the right enclosure , WILL GET so fu[ken LOUD!!!! Awesome SQ and SPL.I had 2 just for show purposes.One sub alone was all I ever ran for everyday driving.More than you'll ever need for everyday use, beleive you me. I myself just ordered an 18", just waiting for it now, build the enclosure and everything.