I think a 50% increase in capability from 4:1 to 6:1 is very significant
You mean a hypothetical increase in capability, based on it working completely as advertised, which it has been established is not the case.
Just to illustrate the point that so many people are trying to make to you, but you seem to be missing; the F3 had a top speed of mach 2.2 as a high level interceptor. However, what we got was something that was quite asthmatic at high level and I NEVER got it close to M2.2.