I wouldn't touch the rear sway bar unless you had a BMR lockout kit or Steeda IRS supports first and if you're that damn good of a driver. The rear bar seems to be well matched to the car. Maybe rear sway bar end links
I'm considering slightly more rear bar on my car but I'd want to couple it with more rear aero. At my home track the car doesn't like to rotate in the slower stuff but at speed it pushes the back end. I think extra aero and a heavier bar might help out in both places.