Audiobahn makes some really great subs, but just like any company worth a ****, their subs are specialized for different applications. some are for sound quality (the alum series, and the natural sound series) and some are simply for SPL (the AW series, and the AWT series). the link you posted didn't work, so i'll just give you a quick rundown. keep in mind that this is only my opinion, and there are probably a lot of people who will disagree with me, but this is what i think after listening to them.
Alum Sound Q Subwoofer (10, 12, 15): Good, powerful, clean SQ sub. They sell all the time on
ebay for $110/each for the 12's, and you can usually find a deal on a pair. It takes a lot of juice to blow them up (or a really shitty install!) but it can be done. I've also been told that they have a tendancy to freeze up if they get too cold. Don't even think about trying to run it off a cheap amp, cause it will only sound as good as the amp you push it with.
AW Natural Sound Subwoofer (831, 1051, 1251, 1571): These are cheapies. Don't even bother with them, because you'd be better off to just come off a couple extra dollars and buy the alums. The only thing I can say that's good about them is they don't need a lot of air space, and they have pretty accurate response for the price.
AWT Linear Compression Woofer (10, 12, 15, 18): Not a bad all-around SPL sub. I mean, the magnets weigh a little over 15lbs, and it'll take 2000+w RMS and keep on ticking. that in itself is impressive as hell! Nice deep bass, a lot of boom, but if you like accurate bass, you'll hate them. They're a bit "sluggish", especially when you hit a lot of fast deep notes in a row. There are better SPL subs out there, but not many in the price range.
AW Pro - Pressure Woofer (1008x, 1208x, 1508x): SPL use only. These are bad-ass subs when it comes to making your adams apple throb, but other than that, they aren't anything special. They're also a bit pricey. They'll take a lot (and i mean A LOT) of power, and they look mean to boot, but unless you're using them for ten second burps at competitions, this probably isn't the sub for you.
Audiobahn makes cheaper versions of the AWT series and the AW series, but it's worth the extra money to buy the competition grade woofers. The numbers i listed beside the series names are the ones to look for, and anything else is just a cheaper version of the same thing. They make a couple other series, but i haven't had the pleasure of hearing them. if anyone else has, please feel free to put your two cents in, and if you disagree with me, also feel free to chime in. I hope i helped you out at least a little, but again, remember that this is just my opinion. One man's junk is another man's treasure.