After having power issues and ABP not being able to find a fault i took it to audi. Only 10 mins of looking at it and the find there was a slight crack in the dump vavle, there was also a air mass meter coming up on the diagnostics............. The techinican changed the dump valve and the car has power again! only prob now is the power is weak and has huge flatspots through the rev range with the boost coming and going! He has advised me to change the air mass meter and go from their. Does this sound like a air mass meter problem, they are charging £105 to buy and fit. Any help appraciated, Thanks.