I have been stuck inside the last couple days and for the next few days in the future due to bad weather....so in the mean time I started getting my numbers lined up from the pit calculator I was so graciously linked to. These are my numbers. I have a 250 gallon tank which comes to 57750 cubic inches. My firebox is a 100 gallon tank which is 23100 square inches. The recommended size was 19250 square inches so mine works out to be 120% of the recommended size. I will do two exhaust pipes one on each side 5 inches in diameter and about 30 inches tall. My firebox intake below the grate will be a 16 in by 4 in square hole with a sliding adjustment door and I am thinking my firebox to cook chamber will be 18 in by 10 in square with a deflector plate angled down to try and decipate any heat that might build by the opening. I think these measurements are correct and I might tinker with my FB to CC opening in order to make it longer and skinnier. What do yall think?