This is a 100% incorrect statement when it comes to the MED ECU in the Fiesta ST.
Even the OEM programming makes use of dynamic ignition timing and fueling. The car will show power improvements with higher octane and more knock resistant fuel. It's very easy to see how it works if you look at the ECU tables and programming. It's also been proven:
http://www.fiestastforum.com/forum/threads/10046-Second-FiST-2016-Fiesta-ST
Even the OEM programming makes use of dynamic ignition timing and fueling. The car will show power improvements with higher octane and more knock resistant fuel. It's very easy to see how it works if you look at the ECU tables and programming. It's also been proven:
http://www.fiestastforum.com/forum/threads/10046-Second-FiST-2016-Fiesta-ST
We are ALL learning here!