Tdi turbo problem??

[avspider]

Hi, i have recently got an A4 tdi avant 110bhp, but it does seem as if the turbo is weak or on the way out, i can hear the high pitch whine in first gear as i pull away slowly, but in 2nd and more i can hear a more mettalic noise and black smoke from the back, not just the normal puff, but while i have my foot hard down from 1krpm to just over 3k rpm.
Any idea's

A