I have no errors in VCDS but my car has been doing some strange things boost wise recently! Firstly I have had a strange fluttering noise since I first bought the car and it only does it when the engine is cold then it goes away when warm. And secondly my turbo has been getting louder as if the boost has been turned up and its spooling faster than normal! Is there any real way to diagnose the N75 valve? I seem to remember reading something about being able to log the N75 in VCDS and be able to see when its working? Any help appreciated guys.