Boost Whine?

[ian2000t]

I've got an annoying whine on boost (comes in about 5psi). It's not like a normal turbo whistle - I have that aswell which is fine.

This sounds more like someone actually whistling, like a boost leak. It's been like it since I did the headgasket which is probably knocking on for 12 months ago now.

Since then I've had every peice of boost hose on and off, and when refitting have refitted them very carefully so they don't leak. So, I assumed it was the inlet gasket.

Well, yesterday I finished fitting the N/A manifold, carefully fitting it with gasket goo and letting that go off properly before driving it. But the whine is still there. When I did the inlet manifold I found a couple of exhaust manifold studs were not fully tight so tightened them up.

Any other thoughts what it could be? Could it be the turbo itself? Such an awkward thing to find, as you can't get boost on the driveway!