Coilover Spring and Shock Assembly. Kit GM Pro Coil Alum R-Adj 9-650 Front C5/C6. Front Pro Coil Drag “R” Series adjustable stock mount shock kit. Compressed length of 11″ and extended length of 14.9″. Includes 9″ spring with rating of 650 for use on a C5/C6 Corvette.. QA1’s Front Pro Coil System is designed specifically for your C5 Corvette. Every shock is 100% dyno tested and serialized, ensuring quality straight from the factory. With three spring rates to choose from, along with double adjustable, single adjustable and Drag “R” Series valving options, you are sure to find what you need for your C5 Corvette. Choose a spring rate and adjustability that fits your driving style, adjust the valving to match and you are on your way. These shocks also utilize a fully threaded body that allows you to adjust your ride height for the perfect stance or to finely tune the weight balance for superior handling.