which bar do you have? most of them are adjustable, move the brackets closer together to reduce the effect of the rear bar. my no bar car was oversteering on that surface with 43psi front 38psi rear so keep that in mind as grip increases as does body lean hence the need for more roll resistance. (now my springs and rear beam are stiffer then your stock stuff was but only by 20%) what works on zeypherhills will not work on concrete. I was getting so much more cornering grip even at Z-hills my car was slamming from side to side. more then it was transisitioning. thhis is partly why even with the increased grip of the new tires I was not much faster then I usual. I could use more -camber too. the outside edges of my tires are showing the effects. and the rear tires are only worn in the middle 2/3 so I'm gonna lower pressures and try and get some Legal camber. or some bolts for when I run Non-SCCA events.