Lambda numbers

I didn´t understand so weel when you mentioned about the scenario when running 0.75 lamba on supercharged and 0.85 on aspirated. Could you explain this a bit better?

Supercharged or Turbocharged cars require more fuel to safely keep the cylinder temps lower than a NA engine needs, hence why you target lower lambda on a forced induction engine.

Tommy has summed this up perfectly - We need to match the fuel delivery to the engine load. As we increase the load on the engine we need to add more fuel and run a richer mixture to control the combustion temperature.