If Curtiss was given the go-ahead to manufacture a "new" P-40 replacement for the late war period, which would be better, The P-40Q with its two stage Allison, cleaned up aero and bubble canopy, or the P-60A (turbo V-170) or P-60D (2 stage Merlin) with its laminar flow wing and revised cooling systems? An alternative may also have been a P-60 with 2 stage Allison (don't think one was ever built). We can ignore the R-2800 P-60s (P-60C and P-60E) because that would require a lot more rework for production lines). The XP-60 (Merlin 28 ) was about 20mph faster than the P-40F (V-1650-1/Merlin 28 ). Which has more long term potential?