"I do not know the factory recommanded position. For the position of the vents on my own airplane, see attached picture. They are very effective but the pilot side vent used to have a tendency to recycle exhaust gases at high angle of attack with the engine at low power, so I had to close it before approach and landing! I had to extend the exhaust pipe two inches to solve that problem. So I believe a higher and/or more forward position of the vents would have been better.
I hope that helps.
Regards
Remi Guerner"
Y10-03-10
