Luftablass Pfauchen wie bei einem Wastegate beim VTG Lader ? | Posts 16+

As previously mentioned, the noise is coming from the intake manifold or the air filter housing. It's caused by overlapping pressure waves generated by the slight imbalance in the compressor wheel and, to some extent, the turbine wheel. Because I work with BMW vehicles daily, I'm familiar with this problem, as there's a service bulletin about it.
I'm hearing the same noise on my AFN. Honestly, I don't feel like replacing the turbo just because it's making a whistling sound!
According to BMW, nothing can break as a result, but in the event of a customer complaint, it needs to be replaced .

I drive an AFN with a modified VNT-17 turbocharger.
Sometimes I use an open BMC filter. When it's installed,
The turbocharger makes almost the same noises as a turbocharged gasoline engine.
with an open pop-off valve. An extremely loud noise occurs with every change in load.
I can hear a hissing sound. It's so loud that it becomes really annoying after a few days.
When I reinstalled the original air filter housing, the noise almost completely disappeared. The air filter housing provides better sound dampening, which is why it's no longer noticeable.
However, I've noticed a significant decrease in performance with the open filter.

Thank you for your responses!

Now I finally know where the noise is coming from. If it's just an "acoustic" issue, I can live with it quite well.