Actually I (and in my opinion no one else) needs to expand on anything.
Lets sum it up
The P39N1 operating at temperatures that were higher than normal acceptable operating levels turned in a good performance but it should be noted that this was at the cost of a very low range and without any payload. This operating at above normal temperatures is no small thing. You can get away with it for a certain period of time but sooner or later it will bite you.
The Typhoon another aircraft of a similar era matched the performance of the P39N1 in the early years and comfortably exceed the performance of the P39N1 from early1944 on. It should also be noted that the Typhoon carrying 2,000lb of bombs had a greater range than the P39N1 when clean and about 1,000 miles with drop tanks.
There is no doubt that the P39N1 has a better performance than the Typhoon at 25,000 ft but the range of the P39N1 would be close to miserable at that altitude and the chances of a successful interception low, make that very low if your spotted when climbing up.
In the real world if you were fighting Typhoons then at 25,000 ft you would be taking on the Spit IX and good luck with that. Even the Spitfire had a better range than any version of the P39 from late 1944 on, and no one would claim that the range of the Spitfire was it's strength.
You can of course add additional fuel tanks but then you effectively end up with the P39Q which has a much lower performance. You can of course tweak the performance by removing the two 0.5 in the wings of the P39Q but that would make little difference to the speed. Worth noting that the Me109 with 2 x 20mm underwing guns only lost 8mph when carrying them and the 0.5 was a lot smaller so the difference is likely to be no more than 4 mph.
You have a lot of fantasies about how to change the performance of the P39. New engines, removing armour, adding fuel tanks, deleting equipment with hardly any evidence (because there is next to none that exists) to back up your assertions that such changes were Easy, Obvious, Simple, Straight forward. Yet has been pointed out to you on any number of occasions, tens of thousands of flight engineers, hundreds of engineers/designers at Bell and thousands of pilots many of whom fought and died in the P39. Educated, trained and experienced people who knew every bolt, cable and rivet in the aircraft didn't make those changes. Why, because they knew it couldn't be done. Yet you, with no training or experience know better than all these people
I was an Artificer in the Fleet Air Arm specialising in airframes and engines. This was a training regime that took five years and I know that your statements and assumptions are puerile. I use that word deliberately because if you look up the definition, it fits. There are many others on this forum with infinitely more training and experience than myself in aviation, these are people I listen too and learn from, people who have also told you with supporting evidence that its impossible. Yet you again, know better than all of us.
No, we do not need to expand , you need to expand to give evidence to support your massive assumptions, and/or explain why you have such omnipotent knowledge on this subject.