Has anyone heard or used an underseat subwoofer like this?
http://www.crutchfield.com/S-1gsE0JK...-THb-200A.html

(I'm well aware of subs in the boot so please avoid recommending it).

I'm not after an extraordinary amount of bass - just something to give it more kick.

Are they worth it? Is it a waste of money? Is wiring it up a lot easier?