There was a guy who did won a Dutch national and noticed afterwards he had run it on 16%, his dad picked by accident a wrong can of fuel for the main final.
I have runned several clubraces on 16% without changing the engine and in the feeling you will not notice something, maybe a little less power in the midrange and on the laptimes you will see a 0.1 / 0.2 sec difference which can be less with the right shimming..
It is nothing to worry about, lets hope the fuel is getting cheaper with the mass production of 16%. But to think this will solve (a part of) the noise issue... No, I do not.
Speed is only fiction but a 130+km/h MRS4 is for real.