well you got two choices this subwoofer will work in both sealed and ported sealed acceptable to me would be 2.8 cf. each before displacements ported 2.34 cf each before displacements ported to 30.3 hz in ported youll be about 3 db louder in the low bass region to 50 hz and close up to 55 hz but the onlty thing i dont like about the ported is what the accuracy will be like they might me a tad sloppy....your subs displacement is .47 so sealed would come out to 3.27 cf per sub sealed and 2.81 cf per sub ported