The PRC .675 spring kit is a Extreme High Tensile strength design that has been proven many many times to work very well. We've recently made engine dyno pulls past 7500rpm with a steel valve & nearly .700" of lift with the .675" spring kit!
The PRC spring kits are carefully designed and tested. To date there are over 30,000 of the newest version of the .675" springs out on the market!!
