BOx for 08 RE XXX 12" does this sound aright

SO i think ive decided on a box size how does 2.5Cubs tuned to about 30 hertz sound? it will be running off my new Md3d! only question i have is will it be louder with a even bigger box? and how much SQ will i lose by going to 32-34 hertz? and how much spl will i gain? and just a FYI i listen to mainly rap but sometimes rock and i just want this sub to be louder then my current W12GTI off 500w rms in a 3 cubic foot box tuned to 33 hertz! so i think either way it will be better //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif