I actually have no idea, they were a pre-fab box bought in JB, just for the time being as he doesn't have the time to build custom yet.
From what I've heard it's ported around 48hz and is what i'd be thinking about 2 cubic foot, which isnt big enough but it's all we've got at the time being.
Though until this amp came along, running the single one off a single Alpine monoblock there was no problem.