ThunderMax Performance ECM: 2021 - up Harley Davidson®  Baggers.

Boost Your Harley’s Performance with ThunderMax ECM

ThunderMax is an industry award-winning performance ECM designed specifically for EFI-equipped Harley Davidson® motorcycles. This cutting-edge, stand-alone tuning system enhances your bike's rideability and power using proprietary AutoTune technology and wide-band oxygen sensors. Whether you’re a weekend rider or a seasoned Harley enthusiast, ThunderMax guarantees unmatched performance and ease of installation.

Key Features of ThunderMax ECM

AutoTune Technology for Precision Fueling

ThunderMax’s AutoTune technology uses wide-band oxygen sensors to continuously adjust fueling points every 1.5 degrees of throttle and every 256 RPM. This results in a smoother-running engine with precise control over your bike’s fuel map, ensuring peak performance at all times.

Easy Installation with No Wire Cutting

ThunderMax is delivered 100% assembled and ready to install. Simply replace your factory ECM and oxygen sensors with ThunderMax, load a map, and you’re set! No wire-cutting or splicing is required, making it an ideal solution for both DIY mechanics and professional installers.

Real-Time Feedback for Optimal Performance

The built-in barometric sensor adjusts for ambient air changes, ensuring consistent performance no matter the conditions. Wide-band O2 sensors provide live, real-time feedback to the ECM, so changes are immediately written to the system once the key is turned off—no need for manual acceptance.

Full Customization with ThunderMax Tuning Software

ThunderMax is fully adjustable using the ThunderMax tuning software, allowing you to fine-tune the system to your exact preferences. Alternatively, you can simply load a pre-configured basemap and hit the road. The choice is yours, giving you ultimate flexibility in how you tune your Harley.

Why Choose ThunderMax for Your Harley Davidson®?

With ThunderMax, you get a highly advanced, reliable tuning system that ensures your Harley runs smoothly, efficiently, and powerfully. Whether you’re looking for simple installation or full customization, ThunderMax is the perfect choice for serious riders who want the best performance and rideability from their EFI Harley Davidson® motorcycles.

Installation Instructions

Emissions Notice

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 products.

Part Number: 309-591

*Excludes 2023-2024 CVO®(VVT)  and 2024-Up Center Cooled Motors

Trike Models with RDRS: Please email support@thunder-max.com prior to installation for an updated firmware file.

Fitment:

2022–2023 FLTRXST Road Glide ST
2022–2023 FLHXST Street Glide ST
2022 FLTRKSE CVO Road Glide Limited
2021–2024 FLHRXS Road King Special
2021–2024 FLHTK Ultra Limited
2021–2024 FLTRK Road Glide Limited
2021–2023 FLHX Street Glide
2021–2023 FLTRX Road Glide
2021–2023 FLHXS Street Glide Special
2021–2023 FLTRXS Road Glide Special
2021–2023 FLHTPI Electra Glide Police
2021–2022 FLHT Electra Glide Standard
2021–2022 FLHXSE CVO Street Glide
2021–2022 FLHR Road King
2021–2022 FLTRXSE CVO Road Glide
2021 FLH Electra Glide Revival
2021 FLHTKSE CVO Limited