Just installed mine. A word to anyone else who decides to do this. The OE screws go into plastic of the body. I installed the shims being very careful not to over tighten... However, since I never used the camera much in the past due to it's useless angle, I never noticed that the camera was in its bracket a hair crooked. Being OCD, the camera and bracket came back out numerous times until the horizon was level.... and by that time, one of the screw holes was stripped. I found a longer screw and all was well in the end though... Anyways, check your camera is level before snugging things up. There are only so many times those screws can come in and out... Oh, and I put a dab of silicone on the back to prevent the camera from rotating in it's bracket too.
The end result was a very useful camera angle. Thanks much to TT for a quick, useful mod...
PS: If it still looks off, it's just the way the background is rendered. I spent 20 minutes centered in front of my garage door playing with it....LOL