How to Set Preload
Setting Preload. This applies to all Cygnus Performance coilovers for all Subaru applications:
The preload values are 1/4″ front and 1/8″ rear.
In order to set preload you need to first loosen the lower spring perch which is the collar at the bottom of the spring (start by loosening the 5mm hex cinch bolt then use the included spanner wrench to loosen the perch itself). You want to make sure the spring is not compressed at all. From there measure the free length of the spring. It should be something close to 7 inches, but because of the way the springs are cycled at the factory it could be a bit shorter or even a bit longer.
Once you have this number tighten the lower spring perch until the spring length is reduced by the desired amount of preload. Tighten the cinch bolt. Preload is set