As above,
it's been a feature of pretty much any ECU built in the last 25 years.
It's a cat saving and fuel saving device.
Nyet, I have done some work with leaded race fuel, which is pretty much completely knock proof, but I haven't come to a definite conclusion yet. I suspect though that best power will be around 12.5:1, and pretty flat from 11:1 to 13:1. ECUplot is really helpful for stuff like this
Rick