That's interesting, Mike. I have them on my OS 1.20's and... well, I guess I ought to clarify that. I have never run the engines without deflectors so I don't know if there would be a decrease in power. But, the planes seem to have pretty much unlimited vertical with those engines, so I would say that they work ok with the deflectors.

Now..can you imagine the Protege with OS 75 AX without exhaust deflector.. if indeed they do rob power? WOW!!

Did the deflector seem to change the tune point? Require more lean/rich mixture?

Dick.