After calming down from laughing hysterically for 20 hours or so I have been thinking about this quite a bit. I think it has to be a combination of mapping and muffler design. There is a spot in the map that is dumping fuel with the right combination of exhaust velocity , back pressure and a design flaw in the muffler that is allowing it to retain raw fuel in the muffler.
I suspect it is a portion of the map where cat is compensating for the valves just about to be opened. They have always struggles with that portion of the map being very fat. The "tip-in" spot in the map where the valves are about to open is tough for servo operated valves.....even if they are staged. Polaris did a great job in this area of their mapping
This is my theory only