Its big when you consider just a few days ago, it wanted 4 cubes sealed. We had some treo talk on here a few times, they seem like good subs, however, the lack of a online availability the small dealer network and the high cost have put them out of the game for many of us, kind, similar to RE Audio and Audiopulse, (although AudioPulse is still available through PE).
Ultimately, the driver seemed to want larger boxes due to its lower power handling though, with the old specs, I would have wanted to dump 2-3kw into it in these small boxes. With the larger boxes, I feel ok just powering it with 1-2kw. I think we need a 4" VC driver with ~35mm xmax, ~50mm xmech with a solid 3kw power handing priced at about $650 with small box demands, similar to the Acoupower 18, but with a lower qts and fs and not quite as insane of power handling or tooled parts. Kevin wouldn't have too big of a problem doing this, the Maelstrom needs added mass anyway to meet spec, if he just upped the vc size and used a similar style motor, he could easily accomplish this. The issue would become finding a basket that would work with it, 10" spiders would be needed, as well as nearly 4" of total clearance. I suppose if he charged $300 more than the Maelstrom, it might be possible.