The P-47N was a great airplane that at +30,000 was much better than a P-51 (any model), but by the time that was realized there were countless P-51's and the war was seemingly headed toward an end.
The N had Slightly better performance than the P-51B-15 @75" WEP with racks and full internal load at 30,000 feet and slightly inferior performance (climb, speed, turn) to the P-51H with racks, full internal load @90" WI WEP at 30,000 feet but the 51H outclimbed it out ran it and out turned it from SL all the way up to 29,000 feet.
If there were such a thing as Allies 46' (like the Luft 46) things would have been different for the P-51 in that environment. Yet it was not that the P-51 was ever massively better than any other plane of its era but how quickly and effectively the Allies could match ratios of 10-1 or more Mustangs against the Germans on a consistent and ongoing basis.
It has been said more than a couple of times that a.) there were never any simultanous examples where all the ETO P-51s were in the same airspace as all of LuftFlotte Reich's single engine fighters...If such was possible, to cram 14 Mustang FG's with an operational deployment per mission of 48 per group until Fall 1944 when often 60+ would fly an A and B mission. LF Reich had between 450 to 525 operational S/E fighters in Germany with another 150 to 200 in France and Belgium between Jan 1, 1944 and August, 1944.
To Look at Jan 1, 1944 - 354FG ~ avg 35-40 per mission, LFR ~ 400 S/E and 130 T/E day fighters
February 20 (Big Week) - 354 and 357FG ~ avg 40 per mission, LFR ~ 450 S/E and 120 T/E day fighters
April 30 ~ 354 and 363 (9AF), 4, 352, 355, 357 FG ~ 40-45 per mission per Group, LFR ~ 450-500 S/E day fighters, 80 T/E.
May 30 ~ 354, 4, 339, 352, 355, 357, 359, 361 FG ~ 45 sorties per Group, LFR ~ 500 S/E and 60 T/E (deployed east of Berlin and Leipzig)
What this means is that by D-Day the average number of P-51B's, to escort Three 8th AF Bomb Divisions, comprised of an average of 10 BG's per Division - each BG flying an average of 40 B-17/B-24s per Group - was 2-3 FG's of 45 Mustangs each to escort 400 B-17's (or B-24's) along a thirty mile string to the break point (defined as the point where some bomb wings set a new course different from the others to attack a different target - therebye further diluting the escorts.
Net - to 'get 10:1 Mustang to LW ratio', the LW has to attack that airspace basically covered by a single P-51 Group. The math says that the standard LW attack was a flight of four attacking a 5 mile region covered by 45 Mustangs.
Even so, the Mustang escorts would deploy perhaps one flight to chase them - reducing the ratio to 1:1.
Conversely, given scenarios like March 29, June 20, July 7, November 26 - the LW would direct 6 to 8 Gruppe's to attack that same size volume when they detected light escort or a Bomb Wing far off course. Then the ratio reverses to as much as 4:1 in favor of LW day fighter to Mustang.
When the crucial battles were fought and won by the Mustang, only the P-51B