Aluminum heads $ per HP?

FWIW.. where folks get mislead on the temperature matter of the head material is that they think of the peak temperatures and pressures... but that only applies to the tendency to detonate.

For the matter of power, that is due to the change in pressure/temperature of the gases in the chamber from start to finish of the expansion cycle (power stroke). If you start the power stroke with a higher chamber pressure/temp, then you will end with higher pressure/temp too, but the pressure/temperature change is from start to finish is going to be the same.... or at least close enough to not see any measurable difference in the energy extracted. (This assumes equal compression ratios, which is what was done in the tests cited by PRH.)