I hear that, and with the engine behind you, the sound probably isn't so bad.  Thing is, I have watched the ongoing discussions of exhaust problems that most have been having with 13B's, and naturally my concern is both sound, and longevity.  The turbo version of the 20B is supposedly pretty quiet in comparison, we'll see.  What are those vents on top of the wings that we see from the rear in the video?

The consensus around my hangar is that the sound is no louder and no less pleasant than a Lyc.  It’s just that mine is unique – sounds more like a twin. But I have both tangential muffler and resonator.  I am also concerned about longevity, which is why I chose inconel for the headers and tangential muffler; and further support the system near the exit.

Those are for the exit air from the wing root oil cooler on one side, and a radiator on the other.  Inlets are underneath.

Al