All testings to be done with 100% fuel.
As for the Fw190A-8, it's the fastest non-perked plane on deck with the exception of the G-10, D-9, P-51, Typhoon, and the La-7. The speeds listed by Batz does seem to be way too high, but upon certain situation it is not abnormal to expect the A-8 to pull away from a P-51, albeit for short distances. (Which of course, does not necessarily mean Cave's experience was the norm...)