“In WWII, we had the most advanced fighter (the P51 Mustang). ...” [PGR88, post 36]
Your analysis doesn’t go far enough.
The P-47 was rated superior to the P-51 in most analyses of warplane effectiveness, and in many individual pilot reports.
It was produced in slightly larger numbers (15,636 vs 15,469).
It carried twice the gun armament compared to initial P-51 variants (8x50 cal guns compared to 4x50 cal guns in P51B and C; only the D model and higher carried 6x50 cal guns). It also held twice the ammunition (3400 rounds vs 1840).
It lifted twice the bomb load or more (2,500 pounds vs 1,000 pounds). Each machine could carry 10x5-inch rockets.
The P-47 attained greater speed at altitude and could maneuver better (instantaneous turn rate).
Only in range could the P-51D and later models outdo the P-47 (1660 miles vs 1030 miles). When fully fueled, P-51s were dangerously unstable, demanding very delicate, judicious handling even from the most seasoned pilots. Partly explains the P-51 loss rate: more were lost to landing and takeoff mishaps than to hostile action.
Hermann Georing said after the war: “When I saw P51’s over Berlin, I knew the jig was up.”