Hey everyone! After becoming quite obsessed with the idea of building my own sub, I'm stoked that I've found this website! So, the plan is to build two subs each with two Eminence Lab12C's. First off, I have a very basic question. Is the volume of the port included in the total volume of the cabinet? I've decided on going with an internal volume of 8 cubic feet, a shelf port that is 20 inches wide, 2 inches high, and 18 inches long. Does that sound alright? I'm after a flat response down to 30Hz and decent performance at 20Hz, which WinISD says I will get with the above dimensions. Thanks in advance for any advice!