I was unable to find a thread that had this particular issue so I apologize if this has been answered before. I have a 2002 1.8L beetle. It has started to develop a loud whistle that almost sounds like the "all aboard" whistle that sea captains use. This is not the typical sound of the turbo, that can be heard outside the car when the rpms are high, but rather inside. I am assuming it has something to do with the turbo, but have no clue how that is possible. I will attempt to record it if need be so that I can post it or email it if anyone is interested.
not sure exactly what is causing it, but it sounds like its coming from the gas pedal, and only when i really press down on it. So far it hasnt caused any major problems, but its certainly concerning. I laughed because its a hilarious noise, but im serious about fixing it, if i can. inspection of the pedal didnt lead me anywhere.
Make sue you have a good seal around your air filter. If it is not seated properly it will make a loud whistling sound proportional to engine demand as air is being leaked around the edge of the filter. This will happen with any type engine if it is not properly seated.