[FIXED] Audi S3 8P Diverter Valve Noise | More info
The DV (oem rev D) was shattered even though it was new. Replaced with GFB's DV+ and it's working great.
EDIT: The noise came back. There is a step when installing the DV+ where you have to put motor oil in the DV+ piston. Applying oil again fixes the noise.