nice i am working on a build for my frontier right now
got 1.5 cubic feet from under the seat but it does stick out past the seat one reason due to mounting depth problems
if ya need to raise the seat because the sub is hitting the seat try these out
and screw them into the rubber stops of the seats mine still lock with a little bit of force and gives you more height in the front part which may help if needed
also keep up the good work