Polo GTI 2012 - odd noise!

[GE90]

Hi All, would appreciate some help! I have a new to me 2012 GTI, and at 1000 RPM, moving and static in neutral I get a kind of buzz/resonance. Happens increasing and when decreasing back down. Only happens at this RPM! So, thinking it must be the supercharger magnetic clutch engaging I changed the water pump and supercharger clutch assembly, but still just the same 🙈.

Any thoughts would be really appreciated.

Thanks.

[Dr G]

I'd be looking at exhaust and flywheel.