Jmac, i could really use your help on this one.
what i've always done is (width + 0.75) x (heigth) x (length - 0.75) / 1728.
i add the 0.75 to the width do account for the volume the MDF displaces, and subtracted 0.75 from the length to account for the 0.75 part of the port that's next to the baffle. this seems most logical to me, but there's been much confusion on how to properly calculate it. anyone?