i have an 04 dakota sigle cab any suggestions on getting more bass behind the seat lookin for very flat sub any help???

might be able to fit some 10's back there. Look for ones with a smaller magnet. not as powerful but as a paired set it should be plenty for a single cab.

Rockford made the Punch Z series, and Pioneer makes a shallow sub. They would work really well.

It all depends on how much money you are willing to spend.

I know someone makes a subwoofer that doesn't need a box, so to speak. It mounts up like a normal door speaker. That would be ideal for your situation. I bet you could crame a bunch of those suckers in there without messing with your seat. Oh, another great option. Infinity makes a self-amplified box/sub set up. It's almost small enough to be about to put two under your seat. Infinity makes good **** too.

Blaupunkt makes a sub with like a 2" - 3" mounting depth. I have used several head units and a few sets of their speakers and i have loved them all so far. I was thinking the sam thing you are and after i amped my front and rear speakers it was good enough.

Keep is updated what you get and post pics please!!