A stock leaf will wind up into an S shape with good grip and power. The S/S springs were made shorter and with a stiffer front segment to combat windup. The Caltrac bar's purpose is also to combat windup. I don't see any point or advantage to Caltracs with S/S springs. I you're thinking "some is good so more is better", you're wrong. If you have an issue with S/S springs then you should consider a complete Caltracs upgrade. The split monos will give a softer ride than the S/S springs but the windup will be controlled. Best of both worlds.