You have to put a 3mm washer under the spindle ball stud, which just looks odd. So I dremeled around 1mm off the steering rack (is about 5mm thick, so even 4mm will be more than strong enough) and placed a 2mm washer on the spindle. Now I have zero bump steer.
Make sure the steering link is parallel with the wishbone
Bump steer causes inpredictable steering as the wheels steer during suspension compression. And since a buggy now and then faces some suspension compression, (a lot of) bump steer is a no-go.