Not sure where to list this but what is the rule of thumb, or what is the recommended size for the smoke chimney on a smoker/grill. Its a 275 gal tank that I use with charcoal. I have 2 pipes on it now and they are 1 1/4 inch inner dia to me that seem a bit small I was thinking about a 3 inch outter dia which would make the inner hole 2 and 7/8 . Any one out there got any ideas thanks