Even slim subs won't fair in that box nicely. There is only one sub that I know that is slim and really thrives in that small of a box and they aren't made anymore. Personally I would go Net audio or make my own box and get whatever subs I want to run in there.
don't knock till you have heard it , the reason I went with Alpine type r is because they meet the air space fox has listed, the box pounds extremely hard . Very impressed with fox .
2-12" VENTED SUB BOX
AIR VOLUME: 1.55 CUBIC FEET PER SIDE
DIVIDED: YES
PORT/VENT TUNE FREQUENCY: 35 Hz
MAX FRAME SIZE: 13" Round subs only
MOUNTING HOLE SIZE: 11.125"
1.55 cubes of airspace is plenty for the right sub , I normally do not have a budget when buying sound equipment and wanted a custom box made but after hearing the fox there is no need to do anything else if ground pounding is what you are after. My RFt15001bd tested 1725watts on a bench test going to 2 12's are just plain crazy bass, everything moves in the cab lol