You are way high on pressure. I see most cars with a 315 are in the 14-16 lb range. You need a set of shocks valved for a radial or send yours off to be done. In my experience the 4 link needs to be a tad shorter and have more anti squat than you would run in a slick tire car. You with out a doubt need to do something where the rpm at launch can be controlled. Lots of changes to make radials work especially on an average prepped race track.