Weird sound under boost and when revs drop 1.9 tdi (video inside)

[YSN]

When the revs of the engine drop there is a weird sound sort of like a metallic rattle/hiss but the phone camera cant seem to pick it up properly but if you turn the volume loud enough you can just about hear it. This same sort of sound comes when the car is going uphill but louder. Instead of making a spooling sound it makes that funny sound but the car still pulls very strong, it was dyno'd and made about 147bhp at AmD. A bit confused but I will try and take another video while driving to pick up the sound under boost as well in the meantime any help would be appreciated. Thanks ASN.

 

[YSN]

Thats the power figure it made as standard then it ran remapped for a few days, it is currently unmapped.

 

[audi2.5tdi]

not sure on the noise...

but the remap didnt look to good, 24% bhp increase is ok, but only 14.6% increase in torque seems pitiful!?

why is the map no longer in place?

 

[YSN]

I still need to take more vids of the noise because Ive driven enough Diesels to know what the car should sound like under boost and these strange noises need investigation as small problems eventually become big ones if not rectified but the phone cam doesn't seem to pick much up. Service is now due so is a good time to fix. The map was taken off because my MPG was supposed to increase but to me it seemed like it decreased instead and also I wanted the car to have some more grunt in 3rd and 4th gear but it seemed like it was the same but the company were helpful in returning it to standard.

 

[YSN]