So although the CO2 has been set to the recommended level at idle it will most likely need to be further adjust on the rollers across the full RPM/load range? wont that affect the idle CO2? (higher?).

I've set my CO2 to 3% based on the mappers' recommendation but I have not being able to get to the rollers as yet. Looking at the spark plugs it looks like the car is running a bit rich at idle but seems fine under boost (14psi) with no sign of deonation.