The FSD model is too new for me to comment on. I am used to the "hydraulic" Koni. We had a heavy one ton Ford extended chassis van which was used to transport three PALLETS of batteries. The Ranchos were a slight improvement over Monroe HD gas shocks but the Koni's made a laughing stock out of the Rancho gas shocks. I shared expenses with my neighbor a battery distributor (and a long-term customer). The first time I drove the van with the Ranchos I decided they were destined for the dumpster. Four hundred and some odd dollars later that van drove like a different vehicle. 3-axles of my bus have Konis that had to have highly modified mounts riveted to the frame and axles. More than a thousand dollars for six shock absorbers. Ever see a 2-5/8" diameter rear sway bar? Three hundred pounds. I never have been a talented driver and I need all the help I can get. ;)