This dyno BS actually really puts me off this forum, seriously. Open your fkn eyes, its just a tuning tool - the number is the number it read, if there was a median point for how "all dynos" of all types would read for the same car.... Dyno Dynamics read well below it so are far and away from being the definition of realistic readings.
If 320-330kw was more realistic on that particular dyno used, it would have made it - Dynapacks are very consistant. Who gives a shxt if it would make 320-330kw (assuming certain tyres, wheels, tyre pressures, that traction is there, and what shoot out mode they are running) on some old rolling road thing.
A relative gain is still going to be a relative gain, so lets focus on helping this lad find it.