I deleted the muffler box on my 850 yesterday as it was rusting off and a straight pipe on these cars sound really cool. But ive now noticed and hopefully not related to the muffler delete that as I accelerate I hear a whistle whine sound that appears to be turbo related and when getting off the gas the whistle whine sound goes away.

Ive checked the intercooler no cracks or breaks on the bottom although there is a tiny pinhole on it that im almost positive is from the factory as its a perfect drill hole. Also re-clamped all the hoses from the intercooler, the short hose connector coming from the intercooler to the top of the turbo does have oil all over it though.

Honestly it sounds cool, not a damaging sort of sound, it sounds like performance, but I could be wrong and hoping someone has some insight.

 

Ours did that for years. Car had 255K when I sold it and last I heard it is about to break 300K.....

 

Many turbo engines do this. My MB 350 SDL turbo diesel makes a whistle like an 18 wheeler.

 

Normal sounds from a turbo. Muffler is what cut down the sound.