So every time I drive my evo every time I attempt to hit boost it sounds like a loud whining noise. My buddy was telling me it’s the transfer case death line but when I let off the gas there is no whine at all. I’m leaning towards a vacuum leak but not sure. I have this video of the sound. Any help is very much appreciated.

 

Does it only happen when in or building boost or in vacuum as well? if only when building boost i would say it is probably a boost leak. Death wine is constant so i wouldn't think its that.

 

Only when building boost.

 

More than likely a boost leak, do a boost leak test and report back.

 

Also check your turbo for shaft play. My original turbo with ~120k miles started sounding like a supercharger when boosting. Then I discovered there was lots of shaft play which was causing the wheel to rub against the inlet

 

Well gents it was my turbo that has gone. Thanks for all the help. New build here I come.