from one of your "sources" gscholz
The MiG-25 that was clocked at Mach 3.2 by the Israelis achieved this speed while running from an intercepting F-4 (which can barely manage Mach 2 on a good day--before running out of fuel). Upon landing, both engines in the MiG had to be replaced.
Victor Belenko, the Foxbat pilot who defected in 1976, stated that the top speed of the MiG-25 was Mach 2.8, but flight above Mach 2.6 was difficult because of a tendency of the engines to overspeed. Victor related that MiG-25 pilots were in fact restricted to flying below Mach 2.5 except with special permission.
My God! Look what this thing is made of! Why, the dumb bastards don't have transistors; they're still using vacuum tubes! These engines are monsters! Maybe the Sovs have a separate refinery for each plane! Jesus! See these rivet heads sticking out, and look at that welding! They did it by hand! Hell, the pilot can't see a thing unless it's practically in front of him! This contraption isn't an airplane; it's a rocket! Hey, see what they've done here! How clever! They were able to use aluminum! Why didn't we ever think of that? How ingenious! It's brilliant!
MiG Pilot : The Final Escape of Lieutenant Belenko
it should be noted that your sources all derive their info from a discussion thread and not from an actual "source" such as Russian design companys