Just another thought on the power required by a turbo to provide useful boost pressure. Say you have a NA engine producing 200 BHP, for the sake of discussion a 2Ltr 4 cylinder unit, and you want 300 BHP using a turbo. So, ignoring all the other stuff needed to accomplish this, and all the relevant efficiencies, losses etc etc. In simple terms, power in = power out, so to produce that additional 100 BHP the turbo needs at least 100 BHP from the exhaust gas off the engine to do that. In practice, due to losses, efficiency, etc, etc, it needs more than that. So, more than 75 KW of energy, regardless of the turbo used. Unless I'm getting something very wrong!