I bet it does sound great!! Glad it's working well. I wonder if another exhaust opening, say at around 4:30, would help with the RPM drop. Of course that would mean relocating the pressure nipple to 10:00 or 1:30 or thereabouts The idea of symmetry with respect to the exhaust openings does appeal to the engineer side of me!
Maybe we could HEAR what the exhaust ring sounds like? (Hint, hint, hint.)