MSDIGNITION HEAT HEI Module Digital HEI Module GM CARB EO # D-40-43 HEAT HEI Module High output replacement HEI module with built-in rev limiter Using 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 Produces an incredible 8.5 amps of juice! The Hottest HEI Module you buy-period!