A couple of observations regarding the last four pages of threads.
First, and most important - the P-51B-1, -5 and C-1 were Depot modified with the 85 gallon fuselage fuel tank put those Mustangs in a slightly precarious combat situation until the tank had been drained to about 25 gallons. To get past Berlin and Leipzig and down past Munich on target escort, the pilots had to retain as much as possible and depend entirely on the external 75 gallon tanks except for takeoff and formation assembly. This meant that the Mustang always entered combat with a full internal load out - which no other fighter did! This is an important factor as many of the big air battles occurred when the P-51B/C still had 250+ gallons of internal fuel.
Second, the P-51B/C was responsible for 100% of the Mustang scores - air and ground - prior to June, 1944. The P-51D first flew in early March and was arriving in the ETO In late April for Depot mods at BAD2 and dribbling into the 8th and 9th AF in small numbers late May, 1944. It was the Primary target escort fighter but the P-38J with 55 gallon Leading Edge tanks did have enough range to get to Berlin but only 'just' and except for a few long range raids, it was relegated to target support for those bomb wings going to say Brunswick or Ludwigshafen or Mulhausen while the 51's carried the escort to Stettin, Posnan, Munich. Consequently, the few Mustang Groups in 8th/9th AF were getting the lions share of 'opportunities' and doing so with a diluted force because they had to perform target escort for 30+ BG in a 100 mile trail at different targets at the end of the string.
Next, from an evolution/introduction standpoint the FW 190D, Ta 152 and Bf 109K were 'tweeners' between the P-51B/C/D/K and the P-51H. Another factor which should be considered is comparing any of those above to the Mustang III which the RAF modified with the R.M. 14 S.M. to chase V-1s. It out ran, out accelerated, out climbed all the above. Only the P-51H generating 2200 Hp with 90" Boost could out run this P-51B version.
The 109 pre-150 Octane fuel and 72" boost always out turned and out climbed the P-51D from a level start, full combat load at 250mph and throttling up to 1.42ata/67". It had the same, but lesser advantage over the P-51B/C due to the weight differences (600 pounds less than D/K). Where the comparisons are less clear is a.) when the combat load has changed appreciably. The wing/lift loading of the Mustang at 1/2 internal fuel is less than the BF 109G/K at 1/2 internal fuel so that a 109 engaging a P-51 halfway home on the return leg is going to experience a different set of comparisons, and b.) when the power curves between the DB 605 differs from the 1650-3 or -7 and both aircraft are travelling at say 400mph TAS. At that point the drag load on the aircraft favor the Mustang as it had more available thrust remaining comparatively than the 109 until the G-10/K-4. At 30,000 feet the P-51B/C that had the 1650-3 had just reached its critical altitude while the DB 605 passed that point at 22,000 feet and the Mustang had a distinct advantage (as well as P-47D) over the 109G, including turn at medium to high speed.
Last - a major part of the disparity of combat results fighter versus fighter included the following factors. First, the LW was forced to engage the Mustang where the power curve disparity was greatest - namely above 22000 feet. Even worse for the FW 190A series. Second, the pilot experience and skill set pool for the LW was decreasing as the US/RAF pool was increasing. A caveat, however, is that much of the LW core that was thrown into the breach as replacements from Fall 1943 through May 1944 came from other experienced Staffels transferred intact from Sud and Ost to LF Mitte/Reich as the LW attempted to defeat US Strategic capability to destroy critical German industry. Last, but perhaps most important was that LW Command emasculated LW combat leaders by ordering them not to engage US fighters. On the surface that should limit most losses to bombers and accidents, but a.) the aggressive nature of US fighter pilots was never blunted during the early actions, b.) escaping from fighter aircraft that are faster is not as easy as anticipated and those that attempted to leave to live another day just died tired from the effort.
As to Skip Holm. he was trying to sell a barn full of 109s when most of his uTube promotion hit the air. Additionally, the Warbirds don't engage in WWII Battle conditions with $2-5M dollar airplanes and the cost of rebuilding a Merlin can exceed $400K.. Take off power at 61" in 51 is about as good as it gets. Another factor to consider is that there are VERY few P-51s in the air today that weren't 90% totaled and rebuilt multiple times. What are the odds of a rebuilt bird being 100% factory spec as far as the airframe/wing is concerned?