Well then...you never mentioned that you already installed sway bars. Like 1:1 racing, braking into the corner and accelerating through the apex of said corner really is the fastest way through a track. Hows about stiffening up the suspension as best as possible, duct taping the inside of each tire so they don't grow when you accelerate (allowing better traction AND less friction through turns), widen it out (possibly locate/fabricate some form of wheel widener) and hone your racing skills...that's about the best I can think of, hope it helps.