Usually when it's cold, I'll let my truck idle for about 15-20 mins. When I get into it, the temp. needle is just about in the inside of the normal range. Now, when I take off I notice @ about 1/4 throttle, or letting off the throttle after take-off, I hear a "shushing" sound until the temp. needle reaches normal operating range. If I let off the throttle completely, I can't hear it. It seems to only occur when you have a tiny bit of foot on the throttle then, like I said, when it hits normal temp:GONE. I don't see any decrease in the rig's performance. No sputtering or hesitation @ take-off. And today I checked it up and down(engine, exhaust, and turbo) and I have no loose hardware, no leaks, no evidence of anything. In all my years working on PSD's, I've never encountered this problem. It definitely sounds like the turbo is making the noise, but is it just because it's cold? Has anyone else heard of such? Am I loosing it? Does anyone have a Kit-Kat(I'm hungry)?