I've got a little noise problem of my own with the plastic covers that surround the steering column...there's a slight gap between the upper and lower halves right behind the wheel that rattles when I'm on rough roads or hit speeds above 45mph. I've tightened all the screws/fasteners but it won't subside. Looks like I'll need to implement something to cover the gap.
THAT irritation is the rubber (plastic, whatever) shroud itself. It's rubbing something (maybe itself) when the car vibrates enough, and causing the noise. I had that problem since the car was brand new. The top and bottom pieces don't seem to snap together too well. In fact when you hit the rough road that causes the noise, pressing down on the top of the shroud will make it stop. Right now I've got some butyl lined between the pieces and it helps some, but doesn't fix it. I'm not sure what a good thorough solution would be. I haven't tried it, but cutting a thin piece of closed cell foam to completely line the inside of the top and bottom shroud pieces might do the trick.