Haha, thanx for the history lesson.
However, it did not really answer my question why the power output increases with an increase in altitude. If you are able to maintain manifold pressure at MSL you will not loose any power with increasing altitude, right? But according to the graphs the power output even seems to increase with altitude, and that confuses me a bit
Turbochargers decrease the 'rate of decrease' of power available up to full throttle height and superchargers even increase the power available. However I can imagine that the supercharger, connected to the crankshaft, has a more powerful source of drive than the turbocharger driven by exhaust.
Brgds