eibach springs

Not having had much experience with the newer fox4 Mustangs, I cannot answer with any degree of accuracy, but I can tell you what worked on my '91 GT.

High rate springs up front can tend to make the fron jittery which will kill your high speed corner exit. The mustang is prone to understeer under power anyway, so if anything, you need help planting the front outside tire. Bigger front sway bars might help, but they tend to introduce their own set of problems, plus they don't help much with the rough road surfaces and they add weight in front of the front tires. Definately a bad thing in the already front heavy Mustang. Camber plates will definately help. They allow you to maximize Camber/Caster which is one thing the Mustang definately needs. With the present stock Mustang setup, there is no camber gain during compression which hurts the general cornering capabilities of the Mustang. What I finally came up with was Maximum MotorSports Camber Caster Plates, Koni coilover conversion (Front and Rear) and polyurathane suspension bits (front, rear and tranny). I found that the lowering springs really screwed up the front geometry and greatly increased the bumpsteer. Even with offset rack bushings, bumpstear was noticable. Switching to '95 or up spindles will help, so this may not be a problem for you. When I finally sorted out the rear suspension problems, then I was able to drastically increase my spring rates without creating that "lumber wagon" effect.