Q: Will this arm make my Model S ride harsh?

No. The sealed spherical bushings are chosen specifically to add precision and durability with silent operation, so you sharpen wheel control without the drone or harshness that plain uniballs can bring. The billet aluminum construction is stronger and lighter than the factory link, and the result is improved handling feel rather than a punishing ride. It is a street-friendly precision upgrade, not a compromise you feel every day.