I'm trying to draw up a center port box now. My port is 5 inches wide, the length for what I'm looking for is 41 inches so it has a bend. The box is 25 inches deep so before the bend it will be 21.75 inches, that leaves 19.25 inches.. I know the port along the rear wall is 2.5 inches. Do I divide the 19.25 in half or does it need that going to both chambers?