Drivers share the same dampers as a 8v, but are nowhere near in the same sitting position (ride height), there is a good difference between them and the springs on the driver are not as stiff as on the gti's.
ARB's as far as i am aware the driver does not have them, thought it was only the 16v's that came with them due to the high power.
In essence your mate is wrong, but to bang a set of gti suspension on there is a easy job.