The car is 23 yo Audi - turbodiesel. From the very beginning I've been enjoying its whining sound made by turbo compressor at higher rpms. However, recently I started to notice another sound. It reminds me on a jet-plane turbine making its high-pitch-dentist-drill-like whistling noise. It annoys me...and I am wondering all the time if there's some pending issues there in the charger. I cannot say for sure that it wasn't there before. Actually I think they were always accompanied one with the other, just the whining sound was overly predominant and whistling was barely noticeable. The car still runs like the wind more or less. There are no big black/grey clouds when I step on it a bit.
So, I would like to hear your oppinion if I should start thinking about overhauling it soon.

Chevrolet HHR Turbocharger