On my '10 I had to cut and shorten the panhard bar when I lowered the car and it was filled with steel shot. Later when I got an adjustable bar I noticed a LOT of ringing noise whenever I hit the slightest bump in back. I took the new bar off, unscrewed the rod end, and filled it with shot and the noise went away. The empty bar would ring if I just tapped on it. It needs the shot to change the resonant frequency so it doesn't add to the noise of the car.