I plan on cutting mine down to a tapered one to follow the contour of the tank here shortly. I made the mistake on my 1st time round of putting the chimney opening down into the cook chamber, and ended up with some overly smoky meats from the top rack, and tough temps to control. I now have it cut square and welded on which helped TREMEDOUSLY, but I plan on finishing it up to follow the contour and see what that does.