Clonking sound
 

i am geting a clonking sound when on boost(say holding the revs at 4000rpm)I know that this is not bottom end as the engine itself sounds fine.Geting some whine from the turbo but no smoke out of the exhourst,Thinking it must be turbo but not sure.
Could this even be the dump valve??Any one exsperianced this or got any ideas,Cheers Chris.

Bump:confused: