I hear wistle/noise from turbo when engine is above 1800rpm on neutral/parking. When i driving, on open windows i hear same wistle/noise when rpms are above 1800. Hose from/to inter-cooler are OK.

I recoreded video/sound on 2500rpm not clear sound of the noise

My engine is om642(224hp), without DPF filter(removed)/catalisator(removed).

Is it normal or there is a problem? Please, answers from people with that car/engine or with experience. Thanks !

well it IS a turbo after all. What does it sound like when the engine is actually being used and the turbo is producing pressure? Has the sound changed in any way since you've owned it?

When the engine isn't in gear, it doesn't take much fuel to raise up the RPM's. It also doesn't make much exhaust which is what spins the turbine, so it doesn't turn the turbo that fast compared to when you've got your foot on the floor in 5th gear and are actually boosting pressures. The turbo is spinning in the "audible" range.

You are right, there is a difference of noise when on neutral or in drive mode (3th,4th gear). It's sounds like the air is "escaping" from somewhere. I check hose from/to they are ok, except that NOISE DAMPER has little bit oil on it.

I think the noise come from wastegate. I think, the wastegate is opening when rpms are above 1800/2000.
My questions is, which sensor control wastegate. I know that turbo positioner control it, but depend on which sensor data. Maybe sensor for back pressure?

EDIT: engine is '06 om642, 3.0 V6 cdi

I am confused what engine you have.
Per my knowledge cdi engines do have variable fins on turbo and no wastegate.
Than if you'd have air leak, that would trigger a code.