If you go to JL`s website they have all kinds of info for building the subbox for each model of sub.
Mine came in a box that is two boxes in one, ported, and ment to fit in a suv. They will be taken out and new boxes made (one for each) and put into my sterio system using one of my Lightstars using and active crossover that starts around 80 Hz going down to whatever I can find. These damn things go so low you can see the speaker moving like crazy but you don`t hear a thing, but you feel your belly is moving inside.
I think ToyMaker said the sealed box for a 13.5 was only 1.75 cubic ft and for ported was about 2.23 cubic ft