That was an interesting comparison. The P-38 was strong up to about 36k, but performance fell off quickly as it went higher. In contrast, the P-47D-40 was impressive, pulling 404 mph (TAS) at 40k.
For those following this; from 40k, I executed a nose-low turn, building some more speed and then half-looped back up to 40k still holding 385 mph (TAS). The P-38J has no chance against the Jug up that high. Virtually nothing does, although the Ta 152 isn't far behind the D model Jugs. However, the P-47N is clearly better than the 152 at 40k, both in climb and in speed. Indeed, the P-47N can attain at least 455 mph at 40k.
I'm glad you enjoyed the flight. We hold monthly high-alt clinics to prepare pilots for the reality of high-alt combat when CT debuts.
My regards,
Widewing