Twin Tuner II Fuel Injection Controller - Big Twin/SportsterEasily adjusts the OEM Delphi fuel injection and ignition to match the requirements of performance parts including high compression pistons heads, camshafts, free flowing exhausts, and low restriction air filters add 30% or subtract 20% fuel and retard spark timing up to 10. You can use the mode and up down pushbutton switches to make fuel trim adjustments in the rpm and throttle position ranges required by most applications; the fuel trim value is