The TDI I had does not have a BOV as there would be no way for it to work as there's no throttle in the intake. Thus when you let up on the throttle, it cuts the fuel, that's all. So on my TDI, was a VNT (Variable Nozzle Turbo). It had a vacuum pod on it that changed the nozzle size. That vacuum pod was hooked up to a valve (which goes bad on many of them). All it does is regulate the boost (which is around 20 psi on the model I had). The whistle was the sound of the turbo.
Cicadas come out all at once every 13 or 17 years. Just cause you don't see them (in off years) sure don't mean they are dead. For when they come, they REALLY come in my neck of the woods.
??? Rickb doesn’t like this. It has been years of fun. I recall Zelio’s warm welcome when I joined the Forum years ago. Stay safe, be well, my three wheeler friend.