This car was whistling very loud (see my other video). Turned out it was the common PCV valve. I hear it is best to change the whole assembly, but I only changed the diaphragm and it worked.
OEM NO.:07K103469L
Manufacturer Part Number: BACB13-KIT027
Other Part Number: 07K-103-469-L, 07K-103-469-F, 07K-103-469-G, 07K-103-469-M, 07K103469L, 07K103469F, 07K103469G, 07K103469M