Three easily identifiable lights: green û Fi2000 is adding more fuel, making the air/fuel ratio approximately 14:1; green and yellow lights û these lights will be on in unison when throttle is open more quickly and air/fuel mixture is approximately 12.5:1; red û light comes on and stays on as long as the Fi2000R follows the fuel curve while adjusting to approximately 12.8:1 air/fuel ratio, which is where the engine will produce its best full-throttle power Corrects lean air/fuel mixture problems; eliminates overheating, backfiring on deceleration, hesitation on acceleration or an uneven rpm Can fine-tune the non-acceleration air/fuel curves using the Bluetooth« app Works with stock or modified engines, air cleaners, and exhaust systems Uses T-tap connectors Made in the USA. FI2000 C50 05-09