What you find in the G14 is that there are various engine setups placed in it from May of 44 through May of 45. The later engined models had the better high altitude performance. They are all DB605s, but it makes a difference whether you have the:
DB605A(M) - straight up with the MW50 boost equipment
DB605AS(M) - with the larger DB603 supercharger and the MW50
DB605ASB(M) - with the larger DB603 supercharger, the MW50, altitude optimized with B4 fuel.
DB605ASC(M) - with the larger DB603 supercharger, the MW50, altitude optimized for the C3 higher-octane fuel.
I always figured our AH G14 as a early model one without the high-altitude boost, not that I wouldn't mind having one of the better motor setups.