Oleg never included the WER settings of the P-40 or any of the Zeros and probably just imposed the same limitation on the grummans.
P-40s are missing about 300hp under 5-8000ft, Zeros are missing about 120hp for take off, etc.
It's a very big job to redress all these individual aircraft, as you do some the others all stand out more. Eventually the job is to go through every single FM in the entire sim/game using good info like the documentation at above mentioned site.
I no longer have time to be a modder, but when I've dipped into fm modding in the past, it was always a very huge task before anyone doing it. People have been working on it plane by plane for years, there are so many it is still going to take many years, we'll be old men when we finally say, ah IL2 is completely finished now