I had recently started hearing an embarrassing noise that repugnantly resembled a dump valve noise not unlike Chavvy hot hatches.
This would align with a dip in power, my thoughts were immediately "split turbo hose". I got it on a ramp to find them all in place and in good nick, it was not till a friend revved the engine that I could see the vacuum advance arm had come off and was swinging like Saddam!
A quick re-connect and fit of missing in action 'C' clip and it was right as rain again. Peace and rattily quiet : )

Sorry I didn't take any pics, but as you look up to the turbo from directly underneath it is it is on the nearside of the turbo.

Anybody else come across this?

Smiler : )

First time I have heard that part been mentioned

But hopefully will help others Former Mod/Member, with the most post & Chicken George Arch nemesis