If you can get the Outlaw LFM-1 EX for a good price, you should go for that sub. All it is, essentially, is a down-firing version of the Hsu VTF3. I think it would outperform all the other subs mentioned so far, the PB10, the PB12, and the VTF2. The LFM-1 EX has a more powerful amp, a larger enclosure, two ports, and can be easily tuned for the application. Something else you might look at which is in its league is the Epik Sentinel, which is on sale right now for the same price.