The plastic belly trays (under the engine, in front of the front wheels) on my '08 2.5 rattle when going over small obstacles. They look to be installed correctly. Any harm in removing them? They don't look like they'll provide protection from much of anything, anyways.
On the H6 3.0L there's a coolant hose (to the oil cooler) that hangs pretty low- I'm guessing the H4 doesn't have this hose which is just sitting there, begging for a piece of road debris to come along and smack it?
Yeah, it looks pretty tidy under the H4. I'm not going offroad (on purpose, anyways!), so I may just yank 'em. We don't get much in the way of extreme weather (unless you count humidity as weather) here in 'Nooga, either.
My other idea was to simply wind small rubber bands under the collars on the reuseable 'connectors' that hold the pans onto the bumper/wheelwell liner. My thought was that if I could take up the 'slack' between these components, the rattle would go away.