I have seen photo's that folks have posted using metal elbows to the inside of the chimney opening, directing the draw down to the grate where the meat sits. Please explain the theory behind this mod. Does it really make a difference?? I would think that it would make the upper inside of the barrel much hotter because some of the heat would get trapped up above, if it helps maintain temp I'm all for it ,I'm up for some knowledge. Thanks in advance!