Harvey Gee,
It is with some trepidation that I question your interpretation of 20.7.4, my good friend, but the way I read it you don't have to apply the 1.25 factor to the manufacturer's data - it's a one thing or the other type rule.
I stand corrected and thank-you for pointing that out to me. CAO 20.7.4 (6.1) clearly applies the factor to actuals; (6.3) allows the use of AFM data without the need to factor. I knew that – I just misplaced the information and re-programmed with faulty data!!! I guess that comes with old age.