All numbers about real world aircraft performance are simplifications in one way or other. For example check out Operation Sageburner at the link below.
The Navy was setting records and putting its' thumb in the USAF's eye while they were the only ones with the brand new F-4 Phantom. One of those digital thrusts was setting a new low altitude speed record. That was just over 900 miles per hour at ana ltiude of no more than 125 ft above sea level. I've heard they went as low as 50 ft.
The usual number given for an F-4's top speed is as high as 1600 mph depending on altitude and many other factors. Check the World Records section.
https://airandspace.si.edu/collectio...m_A19690213000
....and if some of those numbers are surprisingly higher than what you find for an F/A-18 the F/A-18 wasn't designed for supersonic sprinting. It's a seldom used capability in combat aircraft and the amount of experience between the design periods for the F-4 and the F/A-18 have shown that..
Speed, engine power and other things depend heavily on many factors. That 2500 is probably a reasonable number for a hypothetical mature TL8 follow on to the TL7 SR-71 that would be using turbo-ramjets or scramjets as the first part of an orbital flight plan.