HOT1979 / 1979 - Application Notes When we decided to manufacture coil spring for the CTS we took our time and researched other springs on the market. With those springs in mind we found a great combination of performance and ride characteristics. Our springs feature a linear rate design, and come complete with urethane bump stops. Specs: CTS V6 1.5" F, 1 1/8" R Spring Rate: Front: 365 (Stock - 300) Rear: 415 (Stock - 365)