Think I found a better setup now.
Car is a Slash 4x4 LCG 1/8 buggy conversion for highspeed on-road usage.
Total car weight 4.3Kg / 9.5lbs
Front axle weight: 1.8kg
Rear axle weight: 2.4kg
Here is the new setup:
Front: Associated blue 83gf/mm, shocks in outer holes
Rear: Kyosho green 66gf/mm, shocks in outer holes
Here is the first try with stock Apache springs:
Front: HPI white 82gf/mm, shocks in outer holes
Rear: HPI white 82gf/mm, shocks in 3rd hole from outer