1) 60 years of common wisdom.
Common wisdom ? wtf is that ? I would venture to say that "common" wisdom has been declining even since...
2) NACA reports that you HAVE seen.
Same NACA reports have been contradictory to other reports such was RAF testing. Almost all of them contradict each other. None of them are holy.
3) British reports comparing 109 to Spitfars.
Spitfires

One mark out of 36 where each had 3 sub variants comapred against 1 type of out 6 where each had up to 16 variants ?
It's like saying all VWs are faster then BMWs cause 1.8T Golf can smoke the M4 !
4) Literally hundreds of books all saying the same damn thing.
And look up the sources for those books. They feed on one another. Mistakes are propagated from one to the next. Anecdotes of the pilots from 60 years again in the middle of the heated fight used for performance comparison ? Get outta here...
And i beg you, don't quote me that BS Johnson P47 vs Spitfire match... even NACA charts show spitfire rolling faster
5) Documentaries all saying the same damn thing. Go watch a few History Channel documentaries.
Yea, i love them History Channel programs. You can find out 3 times a day how US single handedly saved the world from all evil....
The documentaries are good from the historical point of view, but if you want to be technical about planes - look somewhere else.
6) Museums all across the world all saying the same damn thing. Read the descriptions on the billboards next to an Fw190.
Oh, i remember that one. Tour guide explaining to me how P51 could outperform ANYPLANE at ANY ALTITUDE during WHOLE WAR. When asked about 109G/K 190D or SPitfire - "they were all xxxxxxx" ( select your own sorry bellybutton excuse ). When they are condered it always seems to come back to range
Museums are for little children to check otu what "grandpa" flew. Information there is usually very much generic, borderline neglegent.
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It absolutelly amazes me how people in US are willing to discount anything made in russia due to "communist control". I hate to tell you folks but russian engineers have decades long tradition of excellence. Don't let the shabby production and maintenance standards decieve you. The quality of work and designs of Russian firms can put lot of Western firms to shame.