That grossly over simplifies things. The engine in the Spitfire Mk XVI was not the engine used in any P-51. It was a Packard built Merlin 66 with the full throttle height about 1000ft higher and using American tooling thus requiring different tools for maintainance, and that tooling difference is the reason for it being called a Mk XVI instead of a Mk IX. If you compare the performance curves on the AH Spitfire Mk VIII (Merlin 66) with the Spitfire Mk XVI's (Merlin 266) you will notice that the full throttle altitudes are the same. In otherwords the aircraft labeled as a "Spitfire Mk XVI" in AH is actually a Spitfire LF.Mk IXe powered by a Merlin 66 and not a Spitfire Mk XVI at all.
Here we go again. Where's CorkyJr to explain that a Spit XVI differs from a LF IXe in name only? If you added the 109G-14 as a sub for the 109G-6/AS, then you'd a have a counter to the Spit XVI, and everything would be, more or less, historically accurate.Btw, shouldn't the P-51D be there as well?