does anyone know about these kind of noises...it only happens when i rev the engine and it decels it has this very light but noticable rattling/clicking/shriving noise on the back side of the turbo it sounds like if you had a pice of metal on the exhaust when it rattles but cant find the problem

oh it doesnt boost like it use to but then it does it when it feels like it

 

With some luck, it's just a loose piece of heat shield.
When it's cool, go around the turbo & down pipe with a metal tool & tap on everything to hear the sound.

 

also check the bell housing inspection plates, one of those rattling litte bastards made me lose a bit more hair - and I've got none to spare either!!haha