Early turbos (late 70's and early 80's on many makes, not volvos necessarily) were prone to cracked housings. The allowance for thermal expansion and the deletion of gaskets in areas where the gasket was almost guaranteed to fail, are things learned from these early turbo ventures.

The original poster didn't give any specifics and I was just listing some observations of things that some judge making the engine "noisey".

The turbo sputter from the seam leak when cold is not heard by many but is noticeable if the car is accelerated and you have a window opened at least part way and you drive next to a structure that will reflect the sound.

If you didn't meet all these conditions then you likely would never hear the noise.