My buddy has 2 Clarion pxw1051s, and wants me to make a ported box. The manual lists a 3 inch round port whether running 1 or 2 subs. The single configuration lists the port tune at 35.5hz and the double setup lists 31.1hz. My question is why is the port so small for 2 subs. The xmax is 12mm and sd is 330sq cm, as a pair I would think they'll move more air that a tiny 3" port could handle. Thoughts?