No the fuel economy will be very similar at cruise irrespective of what injector you use. We only use larger injectors to give us the potential for more power at higer boost levels. This does'nt mean the car runs rich everywhere else provided its mapped correctly.

However on cars that I know will be used primarily for track days I do tend to run them richer at cruise, but as a normal road car a greens conversion should be the same as standard when simply cruising.