[chopper817]

I know what that noise is!

Its called "Turbo Bark"

It comes from when the turbo spools up and then you let your foot off the accelerator... the turbo has pressurized the piping from itself to the intake manifold/ throttle body (although most , if not all diesels do no t have a throttle body.) SO.. turbo is pushing a charge and then the requirements for the pressure that has been built is very suddenly no longer present.. that results in a "wave" of pressure headed back towards the turbo... Think of it like those decoration seesaw things that have water in them that rock back and forth... so the returning pressure is heading back towards the turbo, when the pressure reaches the turbo, it fights its way back through the turbo vains that it originally entered through causing the turbo to stop and or reverse direction very fast to almost instantly depending on how much pressure the is coming at the turbo...

SO.. If you have a DV or a BOV, it may not be acting right...

could be that its somewhat normal for that motor, but maybe you are now hearing it because of a recent tune where you have added more boost?... or maybe an intake pipe before the turbo is loose or damaged and now the sound of it is actually getting out and not getting muffled through the factory intake and filter...

I know this sound as I also heard it on my SUPER tuned duramax diesel truck...

Try this,.. hive it throttle like you are in the video and instead of letting you foot off the accelerator fast, do it a little slower and you most likely will not hear the sound.

I hope this helped!