Well just rough guessing..Now I dont know what kind of vehicle u have..but I had 2 12" jlw3sd2's...I had them in a 1.92ft3 box, they did ok, but I needed just a little more airspace...So I'd say put them in a 2.25-2.50ft3 sealed box....They will get enough airspace adn should prove satisfying to ya SPL wise, UNLESS u go with a Ported enclosure, now I dont like ported enclosure all that much and w3s are a ***** to get tuned to in a ported box...But u can make it happen(if u know what your doing)...But GET BACK to me if u need additional help..Cause I ****ed with w3s a lot and can pretty much tell u anything u need for them
Blake