I did search for the answer but could not find where it was covered. I'm building a ported box for two subs (Kicker CVR12's). The manual says each sub needs about 2 cu ft with a port area of 3 x 12.5 x 20.5. My question is what do you do to the port when you add an extra sub? The logical thing to me would be to do 6 x 25 x 41 but I cant imagine thats right. This will be a single chamber box. Thanks guys!!