Ok, so you want four JBL GT1081 10" subs in a vented box?

Here are the useful T/S specs for the JBL GT1081 10":
QTS = .4
VAS = 89.73 L
FS = 28.87 Hz

Those are so others can check me but here is what I got:
A volume of 13.713 ft^3.
F3 = 27.07 Hz
FB = 27.66 Hz

-Giovanni One turbocharger. Two intercoolers. All love.