The Twin Tuner II has all of the features of the Twin Tuner and also allows retarding of the spark timing up to 10 to help prevent pre-ignition knocking. The user interface consists of up/down pushbuttons and a bright daylight readable LED display to select and change the fuel trim and spark retard in the RPM and throttle position ranges required by most applications.
Features:

• Not legal for use in California on pollution controlled vehicles – Check local laws before installing