I blew my factory one within a month.. LITERALLY! They suck. Period!
I think they use a 6 or 6.5" sub???
I have been speaking with an install shop locally, and we have come up with an idea to relocate the emergency brake, and put a down firing enclosure in the center console area.
But... if you don't want to go to these extremes
, then I suggest you do a search on this site for a center console sub. I remember a guy that made an enclosure to fit in the factory space. I believe he put a 8" sub in there.
Good luck... and do NOT buy the factory sub! LOL!