GM appears to have developed a spring/bar package that basically "works". Bottom line - rear springs are stiffer than fronts, and front bars are stiffer than rears. I am NOT a suspension engineer, but I HAVE learned some basic stuff that I have shared (in general) here and (in detail) via e-mail/p.m. with forum members. Further, it appears that BG, BC, and KW have computer modeled the Kappas WITHOUT bars, and thus the rates are stiffer in the front. If I were to go 100% trailer car, I just MIGHT go the route of stiffer front springs and NO bars, but even spring rate spread sheet calculators show stiffer rear springs. I am smart enough to know that I am not smart enough, so I follow GM's basic construct. My rear springs are stiffer than the fronts, the front bar is FE3 and rear is GXP/Z0K, and it works great.