FS: CUSCO Compact S Coilovers (SoCal)

[Fastnx]

The reason the Yaris spring rates look strange to you is because the rear spring is not mounted in a "true coilover" position, it sits outboard in a separate spring cup. This location changes the effective spring rate of the spring in comparison to a true spring over shock design. Also keep in mind that there is very little weight in the rear of this vehicle, it has a very short wheelbase, and the trailing arm suspension design does a great job of reducing roll already without needing an extremely stiff spring to do the job. Overall a lower spring rate will allow for better grip/traction and a better ride feel.
The only reason the front rates are so high is because the front Macpherson strut suspension relies on spring rate more to reduce roll and the stock front sway bar is pretty wimpy

So Toyota was way off when it spec'd the stock springs?