not all the time but most, when i shift usually above 3k i get a weird grinding sound for a sec , its not horrible but its def not good. always had it since i got the car. sorry for the poor explanation
exedy twin disk clutch

 

could be chatter

 

it was the turbo....

 

was the comp wheel hitting the comp housing?

 

my exhaust fins were eaten up and it had slight shaft play. so i replace the turbo with a oem. i never heard the sound again...

 

Didn't recently do cams or anything involving possible slack in the timing belt did you? Reason I ask is if the balancer pulley flips 180* out it will produce a particularly annoying resonance.