13 x 40 x 9 = almost 4700 cubic feet. To me, even dual Ravas will not be enough. You will be looking at something close to the SVS PB1-Plus or dual HSU VTF-3s. Perhaps a single or pair of used VMPS Larger Subwoofers with the Megawoofer option may be more to your liking or a used Paradigm Servo 15.