Check out the installation guide here: https://highhorseperformance.com/installing-your-hhp-psi-spring-kit/
In order to run the higher lift cams on the non-variable cam 5.7L and 6.1L HEMI's, you will need to upgrade your stock valve springs. Through our testing which has involved the breaking of many other valve spring combination's that are currently on the market, we have come to find that this special PSI/Manley combination is the best out there. When you make as much power as HHP does with the HEMI's, the weakest part of the motor is the valve spring. Break a spring and chances are you'll drop a valve and blow up your motor. A $25.00 part can cost you thousands in repairs. We run this combination on all of our head and cam cars and strokers in order to prevent failure.
This kit comes with one set of Max Life PSI valve springs, one set of Manley Titanium retainers, and the required valve shims for installing these springs on older 5.7L and 6.1L cylinder heads (8 shims come for 6.1s, to be installed over the valve seal on the intake side). These springs should be installed with the factory spring cages that come on the 6.1L springs. Contact HHP for more information regarding this.
Springs must be shimmed to a 1.800" height.
