Im currently driving around a 2004 Mk4 astra 1.7 CDTi Design. Earlier tonight while driving the engine began making a very loud noise, like a turbo but much louder. I figured that it is coming from the turbo as it only occurs during turbo boost, but There are no tell tale signs of general problems (i.e black smoke, loss of power, oil loss, coolant loss) nothing. Drives just with all the power, but makes a VERY loud noise on boost. It sounds as if air is escaping rapidly, as if a hose has disconnected but as i've said there is no loss of power HELP?!?