does it get louder when you reverse the car? and than go away when your in drive? cause this just started happening to me yesterday, and at first i thought my air filter was coming loose and banging on the side of my wheel well, but the noise was too loud. i checked and it wasn't that. i was thinking maybe the exhaust shield or something??? i have no clue. i was trying to look under the car last night but it was too dark.