HEI Input Mod Kit

High-Energy Ignition (HEI) Signal Mod Kit for MS1 and MS2 This HEI Mod Kit enhances the input signal strength of your MegaSquirt ECU when using GM HEI ignition systems. Originally designed for V3.57 boards, it’s also compatible with V3.0 boards—just remove the factory XG1-XG2 and TachSelect-OptoIn jumpers and install the included header pins and jumpers. Perfect for installing MS1/Extra or MS2/Extra firmware mods, this kit provides a more robust signal input compared to standard MegaManual mods and has been field-proven on builds like the DIYAutoTune Nova. Included in the Kit: (1) Green jumper (1) Red jumper with 100-ohm inline resistor Header pins Compatibility: MS1: Handles the input side only—you'll still need to configure the ignition output. MS2: Complete HEI support—these ECUs ship with correct output settings. For V3.57 ECUs: Rev A and all ECUs built after 03/2009 already have required header pins. Earlier versions (pre-03/2009) require soldering one header pin to the 5V hole next to the processor. Important Setup Note: In your tuning software, make sure to set the input trigger to "Falling Edge" when using this mod kit with an HEI ignition system.