Spit IIa is now so much more inferior to the 109

[Crumpp]

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.

Sure it was running at 12,500 feet on an altitude test stand.