Infinity Basslink... $400 usd from crutchfield... you can install it yourself! Trust me, its easy!

oh yeah... the basslink, if you dont know, is a 10" woofer and a 200 watt amp in a tiny enclosure less than a cubic foot in size. It has a 10" radiator (woofer with no motor structure) that acts like a port, augmenting bass output, but with no port noise.