The P51 we already have is way overpowered. I would vote for removing the P51 out of the game altogether, and while you're at it, the get rid of the LA7 and the stupidly OP Brewster!
perk it all, everything that goes over 360 on the deck, la7, k4, nik, ki84,G-14,152,d9, 47NM,lancs,spit14&16,typhy,temp, p-51d (p51-b can remain free)...actually better perk it too.