Shock Therapy hates the YXZ, pulse if you look into their previous business history you might not want to do business with them. I know I never will.. If I were to change springs I would go Weller or Ebach. The 2019+ cars are not sprung as stiff if you have the duel rate springs. I'm not sure which car he has, but if he doesn't has duel rate springs that's the place to start.Get a dual-rate spring kit from Shock Therapy. All YXZs a sprung way to stiff so that they pass the government role-over regulations.