Review on Optimize Your Vehicle's Performance with Timbren FR1504D Suspension Enhancement System by Rob Clark

Installed on a 2014 F150 and took about 35 minutes. I didn't have to remove the tires and I think the time I saved by not removing the tires was the same as the time I would have saved had I been given slightly better access. I chose NOT to add a spacer, so I don't ride unloaded secondary springs. When I hitch the trailer it squats a bit on the springs, then stops squatting and I drive the trailer on the auxiliary springs the whole time. I noticed MUCH less swaying due to crosswinds and passing trucks. I didn't notice any change in ride quality with or without a load. The instructions on the shim are very clear so call if you want to add one or not.