I run a rear medium bar on mine originally because full size FWD car theory said it'd make the front tip into corners more enthusiastically. In practice it's only really made the rear end more planted but I'm happy with it. I found running both took off what steering I had. The bar isn't meant to be clamped tight so the rear fit isn't a problem. Side to side wiggle is taken care of by the chassis being wide enough to pin it in place.