I always believed that the car reduced/limited boost via the EBV etc in first two gears and that the Gtec chip together with the disconnection of the EBV removed this 'restriction'?
It's a limit on the rate at which the boost can rise IIRC.
The boost rate rise is mapped to engine load. There is a specific map for it and its values can be changed regardless of boost increases which are different maps again. Obviously removing the EBV will bypass this function entirely but thats another matter.