I always clean inside of my rear tailpipe, and it's always pretty clean, I always just get light grey on my rag, never any black.
Is the standard engine lean burn like some of the older ford engines or is it just the better fuel we buy these days.

Your MR200 which will effect it a lot. The engines run rich for MP165, slightly leaner for MP185 compared to 165 not sure for 200

This all depends on driving style though

The 200 is pretty spot on for the mix, after trackdays my exhaust is normally white but normal drving its black inside

so the richer it is the more black on the tailpipe?

Yep