ThunderMax for 2025 - Up Softail® Models

Part Number: 309-606

The ThunderMax Performance ECM is a complete replacement engine management system engineered to unlock your Harley-Davidson’s full potential. Featuring industry-leading wide-band AutoTune technology, ThunderMax continuously optimizes fuel delivery for your exact combination of components, delivering smoother throttle response, improved rideability, and reliable performance mile after mile. Proudly designed, manufactured, and supported in the USA for over 30 years.