I've read people on this forum say that changing the steering damper changes the feel anywhere from "massively" to "greatly".

Bottom line:

The car should feel rock solid up to 150+ mph. Someone on here has done 160+ and one guy has competed in the Texas Mile. No one does those speeds with a car whose steering is that bad.

If your car's steering feels wiggly at highway speeds, it "ain't norrrmal!"