UPDATE.....I received replacement parts for my Red Lion engine that was in my OMP Extra 300. I needed a new cylinder head, "jug" because mine broke at the exhaust port due to running a aftermarket wrap around muffler. This muffler that caused the failure in the cylinder head was also the cause of all my flutter problems. At John's recommendation to run the stock muffler to prevent engine damage, I made the repairs this weekend and put 4 flights on it today. I noticed, or should I say didn't notice the flutter problem on the first past. So I did many passes at different speeds and throttle settings, NO FLUTTER. That style muffler coupled the minimal clearance on the back of the head evidently caused a harmonic disturbance that transmitted thru the air-frame and manifested in flutter. One of my good friends that's a lot smarter than me suggested that could be a possible cause, but we did not consider it to be because of the muffler. Huh, who knew, learn something new every day.

Thanks John!