I wonder if the power reduction is that much? I know it is some, but not sure how much. I do like using the rubber defectors to reduce some of the gunk on the airplane and it tends help muffle the sound. One thing it did that helped recently was illustrate to me that the muffler through bolt had loosened and it was pointing not where it usually points. Also noticed some blackened oil, thought the motor was cashed. Once tightened up, I was good as new.