Injectors have absolutely nothing to do with either the way an engine runs or its fuel economy. Both those things are down to your ECU calibration.

If your mapper is substandard, both those criteria may be poor. If he blames injectors for either poor running or poor economy, find another one who knows what they are doing with your particular management.

Finally, never have an engine where the turbo can either match, or out flow the injectors. Its a foolish choice to make.