need more sound - wanna stay stockISH

I have an '08 DC Sport and right now I like the sound, I'd just like a bit more. The stock speaker just don't do it for me. So my question is what can I add to my stock sound system to add a good sound. Like a bazooka tube or one of those boss bass all in 1 amp and sub things. What have you guys used. I won't tear out my storage area behind my rear seats, but I don't mind putting something in my rear floor board.

 

I have had everything from a couple cheap add on speaker boxes and bass tubes to full fledged systems. Everything other than a full on system replacement is a waste IMO. Could you lose the smaller rear compartment? Even the factory JBL system uses that spot for a sub. reccomend a Clean Sweep, an Alpine PDX5 under the seat, a Taco tunes box for a 10" sub in the smaller compartment behind the 40 section, and Infinty 6.5" omponents in the doors and coax in the rear. That would make for an incredible system retaining the factory radio and not costing too much in money or storage space. It would be better than the factory JBL system too.