Spit IIa is now so much more inferior to the 109

[lane]

Originally Posted by Crumpp

Obviously the RAF was comfortable enough to test it at 12,500 feet on 9-6-39 Merlin III serial number 7491 mounted on Spitfire N3171 up +10.55lbs using 87 Octane fuel.

You've got that all scrambled. N3171 hadn't even flown yet on 9-6-39. The power figures on the engine Inspection and Test Certificate come from "test bed conditions", either at RR, RAE or the dynamometer at AAEE, i.e. the engine wasn't even mounted in an airframe and the engine surely wasn't running at 12,500 feet without an airframe.