my fire box is 24x24x24 square... And that is prob just right, however i think it shuda been a 26x26x26 for a little oversize compaired to the tank size.
Im going with a 36x6" pipe stack...
Here is the link to my build if you want an idea on what im doing....
http://www.bbq-brethren.com/forum/sh...d.php?t=150441