An Enya #3 plug is rather hot and might cause detonation itself.

A OS #8 would be more normal.

Detonation should get worse if you lean it a couple clicks.

Detonation sounds like frying eggs they say. To me the engine begins to sound ragged. Also when flying, you will hear the engine make a tung sound that repeats about in one second intervals.

A confined Pitts muffler deal will cause a engine to act up.