Sorry to raise this issue again but I have struggled to find a sensible answer to this question.

I have had the infamous police siren noise for 3 years. I have had advice that it is normal and other advise that it is on its way out.

I am satisfied from extensive research including from a turbo specialist THAT NO TURBO SHOULD MAKE THIS NOISE.

Drove to Liverpool yesterday - 40 odd miles. Again completely silent on the motorway. On the side roads, at low speeds, the noise is obtrusive, there is no other word to describe it and it is worse, much worse, when the engine is hot after a longish run. At low speeds it pretty much whines all the time - at higher speeds it goes away.

So the issue is this.

When do I replace the turbo?