Trust me from experience with my own caltracs. The rear mono-leaf cal-tracs are opposite of the way a 4 link works. To hit the tire harder you want less rebound. A cal trac car to plant the tire is going into rebound first and the compression is holding the tire to the track. The travel in the front of the car is important as well. I struggled with not enough travel before. Now I pull both wheels off the ground going 1.39 60'.