This seemed to start 1700km into a 1900km journey. Seems to be coming from driver's side, rear of engine bay. It's a buzzing or rattling sort of noise, more a buzz I guess.

Thought it might have been a heatshield rattling loose but can't find the culprit. From underneath the car the noise seems to originate around the turbo and move through the heatshields towards the guard.

Noise is only there as revs fall after getting off the throttle. Car is MY94 WRX. Exhaust is stock. Any ideas?

http://www.youtube.com/watch?v=Zpsd0tb3AAU

http://www.youtube.com/watch?v=5StqStUmq9k

Pulled off the top turbo shield and ran it again. Noise seems to be from the turbo itself. WTF? ARrrggghhhhh

Noise is from the compressor side. It's fucked again. Why?

could also be the other 50million shields on the stock exhaust

Nah, pretty sure something's up on the compressor side. Noise is at 2900rpm and can be sustained under constant throttle.

Being at one particular engine speed (in neutral) maybe suggests a balance problem? Sounds like the wheel rubs on the housing. What's the likelyhood?

your best bet buddy is to take it to any recommended wrx's specialist and let them diagnose the situation

Had a similar problem to urs a while back in the bug eye before I wrote it off LOL. It was caused by the heat shield not being secured tightly.

What's the clearance between the compressor fins and the housing? Is it small enough that a balancing problem could allow the fins to contact the housing?

Check the turbo bracket/mounting to the block. Mine actually snapped and was vibrating a bit...

I suspect you've had the turbo rebuilt. If your confident its an issue with the front housing, get a feeler gauge and see what the clearance is like.

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