Actually just got off the phone w/Mike at Parts Express about the DVC 295-185 as a replacement for the broken driver in my Xsub paperweight...
I described the Cadence box, the interior dimensions and the short port, and he was scratching his head wondering how the sub can go below 40hz. I know nothing about the physics of sound and speakers, but I did say that the 25hz had been substaniated by craigsub. He said they must be doing something with the amp and a crossover to acheive those numbers.