I recently replaced the diverter valve for the later D revision. I didn't notice much different, and no difference in sound, which is fine. Unfortunately the clip that holds and secures the connector to the diverter valve is not so good, so I had to secure it by other means.
Then once I fitted a BSR open cone filter system I could hear quite a bit of what I think is turbo flutter. I've since put the standard air box back in with a Pipercross panel filter and the flutter noise is still there but now very quiet and barely noticeable.
Is this flutter caused by air being diverted back towards the air filter? And/or is this f*cking the turbo. Or is the diverter valve not functioning because the connector is broke/loose?