If the Ki-84 were given the same treatment as other aircraft, given good materiels and good fuel - it will outperform any U.S. plane in just about every catagory except above 20k or so. . . and since we have so few fights up that high, it would become a true poney killer.
In IL2 they did this and it is arguably one of the best planes in that game, in here, its a little nurfed because the Japanese simply could not produce the good fuel needed. However, it did have self-sealing fuel tanks. . . which really helped a lot.
Its a great plane, and I would fly it more. . . but I am tying to master the Yak-9 right now. . .and thats going to take a long time.