I found this on Amazon - Amazon.com: R/T 300 Enclosure Series -318-12 Alpine - Single 12-Inch Slot Vented Sub Bass Hatchback Speaker Box with Labyrinth Power Port for Alpine Subs: Car Electronics
It looks like it comes from this company - RT Obcon Subwoofer Boxes For JL|JBL|MTX|Rockford|Pioneer|Alpine|Kenwood|Kicker - RTBoxes Subwoofer Enclosures
Do these boxes look like they're going to be better than any other generic prefab enclosure? They seem well made with a good porting system that's not just a hole in the box. I really don't want to spend the money to get a custom box.