Well, I am assuming you got a 12-inch sub, since you are looking at a 12-inch box, and I just looked up on Kicker's website and the RMS of that sub is 400watts. Ohms is how much power is actually getting to the amp, if you have it at 2 ohms, it cuts the power of the amp in half than if you ran the amp at 1 ohm and at full power, it also cuts down on the efficiency since you are cutting the power. If you click on this link http://www.crutchfield.com/S-U6VRlG3...10&I=037A4002T
that will send you to a nice Audiobahn amp that gives you 400watts at 1 ohm in bridged mode, and costs $199.99, which translates to probably under $140 on ebay. Now with that extra money, you could go out, and buy some plywood and carpeting to make your own box and have the satisfaction of knowing you made your own box to your specific application.

You may also want to take a look at this... http://www.kicker.com/images/manuals/03CompVRManual.pdf