turbo "rattle" at idle, goes away when revved

[tedtaylor]

51K miles, everest chip, completely stock otherwise, running perfectly fine.

When starting up cold, i'm getting a rattling noise from i think the turbo. I thought originally it was the engine tappets / lifters a bit noisy, but seems the rattle is coming from center of engine down low near turbo. When i rev the engine, or hold accelerator at higher than idle revs, the rattle disappears.

shield is secure.
any other ideas??

[HJ2]

Are you really sure that all the shields are secure?

[simonbuk]

Are you sure its a rattle and not a ticking noise ?

Could be an exhaust gasket leaking ?