Subwoofer Question about JL Audio 12w6v2?

I would bet not. A friend of mine got a L5 kicker 2 4ohm sub and an eclipse 675W amp installed at Circuit City, and they installed it in single 4ohm on a 2 ohm stable amp... They said it would run cooler. Well obviously, because it wasn't pushing the amp so hard... My guess these shops are trained to do this, just because it will keep the product from blowing during the warranty...

As long as you can adequately power the two Alpines, get the two Alpines. Speakers are made to vibrate air. If you have 1 x 12" speaker, you have approximately 36.7" of surface area of a speaker, vibrating air. If you have 2 x 12" speakers, you have approximately 75.4" of surface area of a speaker, vibrating air. Therefore, with the two subs, you have far greater capacity for vibrating air. The RMS power of both subs isn't that much different (300wrms for the Jl and 200wrms per Alpine), so you're definitely going to get more out of the two Alpines. The main thing that will make or break your system though, is the setup. They need to be set up so that there are enough reflections in order to make sure the high point of the target frequencies amplitude, is in the cabin. This is what will give you the earthshaking bass :)