S&S Forged Roller Rocker Arms

There is no data that I can find in regard to gains in power or RPM. I can tell you that these are built much better than stock, so they'll withstand the greater stresses that come with a big bore build &etc. With regard to geometry or lifter clearance, no changes there if you're using this in an OEM Harley engine. These are, essentially, well-made OEM replacement rocker arms that are equally at home in stock or performance engines with guys looking for reliability. It's only if you're using them in aftermarket engines (eg. S&S T-Series) that accept OEM or OEM-replacement rocker arms that you may run into rocker cover clearance issues, of which, S&S recommends shaving a small amount of material off two of the arms and the rocker covers for clearance. This is clearly documented in the included instructions.