Realistically for a 5" travel shock, you're not gonna want to lower it much more than to 2" bump/3"rebound for street driving. The absolute lowest I would ever let the shock "live" purely with a shorter spring would be with 1.5" bump/3.5" rebound, and that would have to be a lighter car and a
very stiff spring, for racing conditions only. And that would only lower the rear end 1" past the max adjustment in ride height from suspension linkage. That's why I would recommend moving the upper shock mount higher or the lower shock mount lower, relative to the frame/rear axle
