Resurrecting this thread, just replaced the intake elbow (old one WAS cracked in multiple places) and removed & checked the DISA valve--it's in one piece and seems OK, but..
I still get a whistling/whirring sound at steady throttle, 1500-1900 rpm or so. When I let off of the accellerator it goes away.
Any other ideas?
Bill

Bill: Change it. The DISA V. is a very important piece. Something is blocking your air intake. Sometime the DISA shows no signs of decay -- like mine, but when you change it -- your Bimmer will act like it's released from an ASTHMA Attack. I fill up on Saturday, runs errands over weekend, Drive 24 mi. each way to work now in two weeks without filling up. This is EXTRAORDINARY! The response now is HEAVEN. And my pockets are not SQUEALING anymore either...

Thx, I'll check around and see if I can get one on the low end of $200.
Bill

You can get one from : BMW Parts - Call (800) 734-0782 for New Genuine BMW Parts and Accessories - Save Money