The all-new 4S progressive springs marked 2.5–2.8. 4S springs have been specifically designed to complement the SLP shocks and are 20mm long. Set of 2.
The main advantage and benefit of progressive springs is that as the car initially enters the corner they work like a C2.5 spring to provide maximum traction. At the same time, when the chassis begins to roll, in the middle of the corner, the spring rate progressively increases until it works like a C2.8 which allows the car to maintain maximum cornering speed.
The 4S springs, like all the other XRAY springs, are manually measured, selected and matched into pairs to guarantee precisely equal length and damping characteristics.