The stage 2 valve springs are rated to hold the most power in the 7.3 Powerstroke. The "beehive" design hold more seat pressure to handle high horsepower engines and prevent valve lift due to excessive boost pressures. These springs are the strongest available and will make a great upgrade to you high performance Powerstroke. Quality and reliability from Comp Cams and we recommended this upgrade for 275cc and higher injectors. For high boost or competition applications. Complete valve spring kit with locks and retainers.