ThunderMax for 99 - 01 Magnetti Marelli® Models
PN: 309-313
**The ThunderMax 309-312 and 309-313 ECMs are designed exclusively for Magnetti Marelli–equipped EFI Harley-Davidson® models. These units will not function on bikes that have been converted to Delphi EFI. If your motorcycle has been converted to Delphi, you will need ThunderMax part number 309-314, available through Zipper’s Performance.
ThunderMax is a performance-driven, award-winning ECM built exclusively for EFI-equipped Harley-Davidson® motorcycles. The 309-313 is designed specifically for Magnetti Marelli–equipped EFI models from 1999–2001, giving these classics modern tuning technology without sacrificing reliability. The kit 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.
This kit also includes a speed sensor wire and sensor harness, ensuring proper integration with the Magnetti Marelli system and a clean, reliable installation.
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 keep the stock conveniences your Harley came with.
Riders get complete flexibility: run a basemap and let AutoTune handle the rest, or dive into the ThunderMax software—free to download from our website—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.
The result? Sharper throttle response, stronger rideability, and that deep, tuned exhaust note that makes the bike yours. Built for Magnetti Marelli–equipped Harleys. Engineered, built, and supported in the USA.
Notice: ThunderMax ECMs utilize 18mm O₂ sensors. Factory exhaust systems are equipped with 12mm ports; however, nearly all aftermarket exhaust systems are manufactured with 18mm ports. If using a factory exhaust, you may weld in 18mm bungs. Bungs are not included.
This product is intended for "RACE READY" vehicles only and is not for sale or use on vehicles otherwise subject to emission control requirements. In the state of California, this product should not be used on any vehicle that is registered for use on public roads. Please view the ThunderMax 50 application guide for "STREET APPROVED" & ARB compliant produ