I bought RacingBrake slotted rotors a long time ago and they are great, still got them. I think Fig is a vendor now, but I got them direct. My rears I bought on irontoad.com or rockauto.com, can't remember.
I think you would be surprised but stock is pretty darn good. Fig sells the adapter so you use your stock caliper and pad, but use the Supra rotor, since the rotor is larger in diameter. If I were to do it again, that is what I would do.
I coalesce the vapor of human experience into a viable and logical comprehenshion.