The UMI Performance spring and shock kit is designed to greatly improve handling and control. Our race-quality springs are made from premium US-sourced CrSi wire, providing high performance for street cruising, Pro-Touring, corner carving, or light drag use. Bilstein gas charged shocks offer a balance of comfort and control. For vehicles with full weight big block engines, there may be an additional 1/4" front end drop. Overall, this kit includes factory height springs with 530 lb/in front rates and 130 lb/in linear rate, along with Bilstein gas charged shocks.