A turbo engine uses the turbo to increase combustion pressure, which also generates heat. The higher octane fuel will combust at higher pressure and temps, so will always benefit performance engines, especially those with a turbo fitted. As it burns cooler, your cat wont get as hot, hence the ECU light not coming on when you use it.
V Power and the higher octane fuels shoudl work better with any engine, but any EU car should run fine on normal Unleaded regardless.
What If There Were No Hypothetical Questions?