You've got a lot to learn, but I'll at least start you off. First off, subs don't produce power, amps do. Secondly, the amount of power a sub can take does NOT tell you how loud it will get. Some subs are more effecient than others and get louder with less power. Third, most company's rate specs differnently, bad companies, like AB, basically lie to make their numbers bigger. They figure if the numbers are bigger and their stuff looks better, unknowing people will think its good and buy it. Here's some of the ways they cheat
1.Peak power: they measure an amps performance while pushing a unrealistically high voltage through it, something you'd never see from a car battery, then measure the watts, if it were to sustain that for more than a second, the amp would fry, but techically it did put out that much power. This is sometimes referred to an ILS figure. (if lightning strikes)
2.They can probably rate subs the same way. Our amp can put out "2000" watts, the sub can take it, so the sub must be able to handle 2000 watts RMS, right? I'd be fairly suprised if that AB could handle a real 1000 watt amplifier, even if it could, that wouldn't necessarily mean it was loud. It tells you even less about how the subs sounds, which AB has a pretty bad reputation there too. There's lot of subs that can handle half the power the AB claims it can that I would rather have in my car!
Assuming your not asking about something you've already purchased, let me know your budget and I can help you get a good sub setup going.