From the INTENSE website:
Comp Cams "OE R Series" Hydraulic Roller Lifters are designed with an increase in internal preload to prevent the lifters from bleeding off. This goes very well with cams like mine and shift points over 6,000 RPMs - which I expect to be seeing in the near future.
The only items left in my valvetrain that are still stock are the rocker arms. Once INTENSE comes out with their 3rd Generation Aluminum Roller Rockers, I plan to purchase those in order to have a completely upgraded valvetrain.
Comp Cams OE-R Hydraulic Roller Lifters