Heat Hei Module High Output Replacement Hei Module With Built-In Rev Limiter MSD IgnitionUsing upgraded components, the HEAT HEI module produces high output for stock and MSD applications plus has a built in rev limiter that is more accurate and easier to set with the engine running. Fits in stock HEI distributors Adjust the rev limiter without removing the cap! Built in adjustable rev limiter can easily be set externally Advanced dwell control for improved high rpm output Easily installs to non computer controlled (4 Pin) HEI housings