Whsts your spec
K03 DSG Revo Stg-1, b8t5f9
 
Thought you had the super dooper new Revo stage 2+ 
Nope - just stg1, set as above.
Jim (?) suggested wastegate issues, and that I should check for a crack in the turbo housing near the wastegate. He also said he'd bet that if I logged boost target versus actual there would be discrepancy. I've checked and there isn't, and the N75 isn't ever hitting 100% except when spooling at low revs, so I don't think there is a wastegate problem.
e.g:
revs      requested      actual
5400      1950      1920
5600      1890      1870
5840      1810      1830
6040      1730      1790
6240      1710      1740
6400      1720      1710
6560      1700      1700
6680      1050      1680
The car drives fine, so I'm inclined to ignore the dyno figures. Hell they theoretically make my insurance cheaper!  

As a slight aside, I logged the g/s whilst on the dyno, and the car was consuming about 20g/s less than it does on the road.