Typical spec for a turbo is horsepower, which I suppose could be back calculated for a rough airflow number.
I believe that max Horsepower of the 1.4L turbo is unknown to most of us, the computer will bleed off the charge air beyond 16 lb of boost.
I would be more interested to find out much boost the stock turbo would safely make across the RPM band without the ECU messing with airflow.
For example my ECO has a peak torque at 1850 RPM compared to other models of 2500 RPM, Horsepower is limited to 138 @ 4900 RPM for all models with the 1.4L.
Going beyond 138 HP which requires a tune and some modifications, however it seems that people tend to upgrade the turbo to get past the 180 HP wall. (might be lower)