I dont see whats wrong with the P51.
I suspect this is a troll.
However, if it aint, if F4u drivers complain the stang is too fast (which it was faster than hogs historically) then why dont zeke pilots complain that the P38 or Niki is too fast?
Some planes are faster than others, some are slower than others, ergo: there are planes that can run from others; and there always will be.
This truly is the most pathetic call i have heard in a long time. Yaks, 109G10, tiffie, even La5 can catch P51s unless its a co-e situation on the deck and the stang is outta gun range then the mustang may slowly pull away - but so what? Mustangs are easy to kill by the aforementioned planes.
If any plane is too uber in this plane-set its the Yak, its as fast as the mustang, turns better, climb better, rolls better, accelerates better and has a cannon.