Last night I finally installed my coils. I went to take the car for a sping, and I hear this really loud metal on metal tapping noise. I had my friend continue to drive the car (only about 35mph max) as I sat in the back to see what was happening.
On the passenger side rear coilover, it seems that everything is tight. The strut is moving up and down with play. Its like while he was driving the car, I literally felt the the middle piece of the top mount (not the top mount, the actual piece connected to the strut) moving up and down each time the noise was made. Nothing else is moving on the setup just that the play in strut and top mount is making the noise, as it sounds like its coming from the inside of the car.
Top nut is loose. Take a air impact gun to the nut on the top of the coilover pull the trigger for one second, should be tight after that and will not make any odd noises.