need subwoofer air space specs

I had two 10" MTX thunder 6000's, in a bandpass box, and an 800 watt amp, in my ranger ext cab, now that i have had a RAM for a few months, i am missing the way some songs sound with some nice subs pumping, any way this box is about and inch too deep to put behind the seats, I am going to attempt to build a box, so thats why i need to locate some air space specs for theese speakers, if i build a one piece box should it be sealed or ported, and should each speaker be in is own space, or double the inside air space and and have it completley open inside. Any other tips and suggestion greatly accepted.

Thanks in advance