ThunderMax for 2021 - 2024 Softail® Models

ThunderMax for 2002 - 2017 V-Rod® Models

The ThunderMax 309-592 kit uses the same ECM as part number 309-591 but includes a specially designed ECM caddy for Softail fitment, making installation clean and secure for Softail models. 

ThunderMax is a performance-driven, award-winning ECM built exclusively for EFI-equipped Harley-Davidson® motorcycles. Designed as a stand-alone replacement for the factory ECM, the 309-466 arrives fully assembled with wide-band oxygen sensors, plug-in harness, AutoTune module, USB communication cable, and everything you need for a straightforward install—no wire-cutting, splicing, or dyno required.

At its core, ThunderMax uses proprietary AutoTune technology and a closed-loop control system to continuously read, adjust, and perfect your air/fuel ratio in real time. With fueling points mapped every 1.5° of throttle and every 256 RPM, the system delivers unmatched precision for smooth, consistent performance in all riding conditions. A built-in barometric sensor accounts for altitude and ambient air changes automatically—just load the map that matches your build and ride.

Unlike other aftermarket tuners, ThunderMax fully supports factory functions, so you don’t lose the stock conveniences your Harley came with.

Riders get complete flexibility: run a base map and let AutoTune handle the rest, or dive into the ThunderMax software to fine-tune AFR maps, ignition timing, startup fuel, idle speed, rev limits, and speedometer calibration. The system also offers robust data collection and diagnostic capabilities, letting you log, monitor, and analyze critical engine metrics for deeper insight into performance