Okay so I removed my hood mounted bug gaurd and I'm still getting that stupid tapping noise that sounds like it's coming form behind the firewall at highway speeds. I think it's possible it's those rubber covers that go on both ends of the wiper linkage trough/tray(whatever you wanna call it). Haven't figured that one out yet though, I'm gonna try taping them shut just to see if that fixes it.

I thought everyone else got the noise to go away as soon as they took off their bug gaurds though.[:@]

 

this might sound dumb, but make sure your radio antenna is on tight. mine came loose the other day and it made a really irritating noise

 

I have the bug guard and window visors and I have no noise at all. I have aftermarket ones on mine. My dad has an 07 silverado and he has the GM ones on his and he gets the annoying flapping sound too. I don't know where is comes from but I know it's not an issue on aftermarket/GM guards like it has been said before.