I found boxes that will fix under my seat and has the minimum air space required. Out of those two which one will hit harder and deeper under my seat(04 dodge ram). I understand I am not going to win any competitions.
^^^What murph said... And the subs are going to be run in sealed enclosures I'm thinking? The RF's and the Kickers are going to need room. A lot more than putting them under your seat.
If you are halfway decent at building a box, I would recommend building a console sub box, and do a 10 or 12,or a pair of good 8s.That would give you more options of getting good subs, and being able to perform much better..I sat in a Dodge double cab that a guy made a covered box for a JL 12,in the front seat in between the driver and passenger, and it was BA!!Sounded amazing on a Zapco amp@2ohms..Consider other options rather than under the seat