Pe, I think I know what you are talking about. THe air gets compressed going through the front openings. As soon as it hits the fins it expands. Now it needs to be deflected in the right direction, otherwise it could create turbulences inside the cowl The reason I positioned the deflector behind the jugs like that was, to seal the cowl on top from the air going behind it and cause these unwanted turbulences. The proof that my concept works is in the measured temperatures. Right after I installed these baffles I flew with a brandnew left jug. Of course the motor ran very rich for initial break in. After my landing (no taxiing back) I ran a few yards to my plane and measured the temp of both jugs. 164° on the right and 200° on the brandnew left jug. A new jug naturally runs hotter during break in. But my system works. The air can only go over the fins and out on the bottom. Do you think I am wrong with my set up? Isn't the temp telling the truth?