PAC 1512 FORD MODULAR ENGINE DUAL SPRING FOR HIGH LIFT AND HIGH RPM APPLICATIONCALL SHANON AT 507 445 3235 WITH ANY QUESTIONS. 1500 Series Premium springs that have a nitride surface heat treatment. These polished and Nano Peen springs have a gold color. They have extremely high levels of fatigue life for the most demanding endurance racing. Weight Outer Spring I. D. Outer Spring O. D. Inside Spring I. D. Install Load Install Height Open Load Open Height Coil Bind Max Lift Max Frequency Outer Frequency Inner Damper Quantity List