are these 12's your running? because 2 cuft seems like a lot to me. old subs used to need very large boxes, but the new ones can use much smaller boxes. if i were you i would use the 1cuft sized box per sub. your best bet for sound clarity is to check the manual for the sub and look up the dimensions for their recomended sub enclosure. that will give you the volume at which the sub is most repsonsive to (with the exception of tuned ported boxes). but remember if you use 2cuft boxes for each your taking up easily half of your truck space.

 

^ the sub gave the dimensions for the box at 1 to 2 cubic feet. and yes they are 12''s i'm running