TC Sounds Axis 15Q1 15&quot; Quad VC Subwoofer
This sub is incredible.  Incredibly musical, takes an incredible amount of power, incredibly strong output.  I own a LMS 4000 and a couple other TC based subs and this one is a keeper as well.  I have it in a 4 cubic foot sealed box in a 08 GMC sierra and just WOW!!!  Quick shipping, great customer service, you can't go wrong.  Just make sure you have space, this sub is a beast.