You can remove the shim if you need to, it's simply there as a fine tune adjustment to the steering link angle.

Most of the problem is that the holes in the chassis plate are too far forward, so if taking out the spacers doesn't help (like it didn't for me), you can try to file a little bit of the bump away from the steering rack arm. The only final cures are to elongate the holes in the chassis, get a different chassis plate(which may have the same problem), or get a different servo.

I've looked at 3 different chassis plates in addition to my own. ALL 4 had the holes in different places not only N/S, but E/W as well in reference to all the other holes in the chassis (which all lined up fine). One was so bad the guy resorted to shaved plastic mounts and bolts/nuts to hold the servo to the mounts to get enough clearance with a "known to fit" servo (AE brand servo).

There's a serious problem with either the CNC program for the drilling of these holes, or the indexing of the carbon plate in the drilling fixture.

Other than that issue, I really like the car.