[_1SMV_Gitano]

That russian test could have been the source of misinformation about Fw190 performances. Infact (IIRC) they were obliged to use a Ju-87 propeller cause the original one was broken. Second point is that they probably used soviet low-octane fuel in place of synthetic C3 fuel.
This was similar when soviet pilots complained about lend-lease Hurricane's low performance, not taking into account that Merlins were suited for the higher-octane british fuel.