the JTS springs are by far the best way to go...4 bar link will not give any gains over the special JTS leafs.
I have them in my coupe and the rear end is fantastic on the car. No tramp excellent stability.
If you are going down this path and want to do it anyway go for an IRS setup out of an Impreza or something that has good ratios, is strong, and will be woth the time and effort.
For track and strip, the leafs are all you need. Especially with a 13B turbo nottoo much torque there