The MiG-25 was the big bogeyman of the Cold War, since the data we had on it was sketchy, and after the supersonic run from Syria to Egypt, tracked by the Israelis at Mach 3. We redesigned the F-16 to go against what we THOUGHT were the MiG-25's abilities, and it turned out that any Soviet pilot would be performing a rather elaborate suicide if he went against the F-16.
Also, remember that the Russians still have two versions of their military equipment. Standard is for themselves, and the "monkey model" for export. The term "monkey model" is for who they believe will be running it.