I was a little hesitant buying these subs at first due to the fact that I was unable to find any T/S parameters for the subs and because there were very few reviews online. A sub with this high of a power rating for $50 usually means poor build quality and lots of distortion, but not so with these bad boys! The T/S parameters are listed in the manual that comes with the subs for system optimization, btw.
I decided to take a chance and purchase 2 of these subs to use in transmission line enclosures in my home theater system. Each of the lines uses a Crown amp (600W), a single sub driver (P126DVC), has an effective length of 12' and is tuned to 16hz. The heavy hitting (I mean HEAVY) power of these subs combined with the clarity and tuning of the transmission lines is utterly terrifying. These subwoofers generate so much slam, its unearthly.
I haven't tried these subs in a standard sealed or ported box, or in any auto application for that matter, but I can certainly speak for their ability to hit hard and command authority, even at low listening levels. I've also pushed these subs with 1000W RMS to test there power ratings, and if you have a well constructed box (and ears that can handle it), the P126DVC will keep up without issues.
Long story short, if you're feeling timid because of the low price and lack of reviews, rest assured. These drivers will not let you down.