New High Quality PIONEER TS SWX251 10 SHALLOW SERIES PRELOADED ENCLOSURE (CAR STEREO SUBS)
This sub hits surprisingly hard for its size. Paired with a pioneer amp(800w max, 200w rms) this sub will make my mirrors vibrate. If you don't neccessarily want bass that is going to break your windows, but want one that can fit under the seat and still give a good bump.