Ginger turbo,

Intercooler was never replaced just internally flushed clean of oil residues tested for air leaks, none of which were found, and re-installed back in place. Oil temperatures are in fact cooler by some 10 degrees C and this I attribute to replacing the factory radiator with a 50 mm alloy radiator. Somehow I have a feeling the CO level is low. I asked the test station operator about this and he remarked that the lambda value was perfect, and that this value was the main parameter showing the quality of the air fuel mix.

I'm open to more advise