Mach 2 doesn't do anything against a Mach 4 missile. As I said, the Arrow would be a good plane to this day, but it could not take on the new generation of aircraft. A F-22, Eurofighter or the new Sukhio or MiG designs would eat that thing alive, becuase they could detect it before it could detect them and if it tried to dash away they could keep pace. Another problem with the mach 2 number is that it uses afterburners to do that, and that sucks up a lot of fuel. So the new generation of fighters, like with the F-22's sonic cruise capability, can go faster for longer durations of time. Against a Mirage, F-15, F-16 or the older Su's and MiG it could hold it's own, but with the new genration it just can't cut it.