Turbo noise diagnosis?

[rrgrassi]

I used to be able to hear my turbo whistle ever since I bought the car.

Seems now the whistle has been replaced by a noise similiar to when one uses the "canned air" for cleaning computer keyboards.

The car runs and drives fine. I did a valve adjustment 2 weeks ago.

This noise only happens as the turbo spools up, and abates when you reach cruising speed. At 70 mph, I can hear it just a bit, it dissappears when I let off the accelerator, but increases when I accelerate, even at 70. I tried listenening with the window down, but nothing abnormal. I can only really hear it with the windows closed. It appear to be coming from the passenger side as I would expect.

Any ideas on what to check? I wonder if the intake gasket is leaking...

Thanks!