Kicker 6.5" CompVT Car Subwoofer 2 OHM 10CVT652
This thing sounds VERY good.  I jacked up the bass output, slave output, cranked the gain and low-passed the speaker @ 150hz as if it was a large sub and it still responds very well.  It took me with iTunes and some serious exploration to find songs it wasn't entirely comfortable with, and nothing was bad, but note that my box is not up to spec, probably 30%-40% smaller than it should be.  For punchy bass and mid-bass, this thing ROCKS and is a secret weapon when I add an 8\\" sub with a bigger box for seri