These are the hydraulic lifters that are matched to the emissions-compliant camshaft Edelbrock specifies for the MPI conversion. This camshaft comes with a CARB E.O. number and subsequently offers slight gains in performance over the OEM camshaft. Ultimately, we may switch to a hydraulic roller camshaft and lifters to see what power gains can be had. There is a fine line between max power and smog compliancy, and we want to find it.