Check for a boost leak, also, check your exhaust mani gaskets. Mine went out in my Talon and would only make the sound at higher rpms as well as when I was boosting.. Just a thought.

 

This is happening to me to. The coupler thats between the turbo and intercooler caught a hole in it. So when i drive it i lost all my power, the high pitch sound vanished. But when i replaced that coupler, i regained power but also revived that loud pitch noise. So i know it has to do with something connected to turbo for sure. Just dont know what???

 

Did you ever get this figured out?

 

i (not op) have a boost leak here. something with the LICP but the clamps are on - do they need to be tighter? in a particular place?

 

I had this issue, for me it was the jpipe gasket. I ended up replacing both the gasket and the jpipe. Also make sure the clamps are on straight and tight, which is kind of hard since its a pretty tight area.