The point of a sway bay in most systems is to equally load the opposite side of the suspension to avoid excessive body roll. A by product of the equal weight transfer is that you can induce oversteer by running a thicker bar in the rear as opposed to the front.
Assuming your alignment is relatively tame, and you havent done too much to induce more camber than necessary from the natural camber increase from ride height being dropped.
You can make sure all of your corners are first loaded correctly with corner balancing (overkill unless you do a lot of time attack), or try just running an aftermarket rear sway - and oem in the front, to induce a bit more oversteer by allowing weight to transfer in the front quicker on transition phases, thus causing the rear to be a bit more wiggly.
14k/12k are pretty high, are you sure these are correct? Most tracked cars stick to 7k swift springs, or similar. I am not sure how you would even break rear traction with spring rates that high, the car must not roll at all or transfers weight too quickly to take advantage of it.
You are actually local to me and also pretty close to Race Comp Engineering, the crew there is pretty good with suspension geometry and might have more ideas.