The Twin Tuner allows easy adjustments to OEM Delphi fuel-injection systems to improve performance and match the requirements of performance parts. Features mode and up/down pushbutton switches to make fuel trim adjustments in the RPM and throttle position (TPS) ranges required by most applications. You can add up to +30% or subtract down to -20% fuel. Fuel trim value is displayed on a bright daylight-readable LED display. Also features an advanced mode using the optional USB Interface ZPN 742001 and PC Link Tuner software that allows precise fuel adjustments and independent adjustments to the front and rear cylinders. Compatible with Power Commander fuel maps. Easy plug-in installation and setup and measures only: 10 cm x 51 mm x 13 mm (4” x 2” x 0,5”).Fully compatible with Twin Scan Tuning Aids. Install the Tuning Aid and ride the bike, then copy the air/ fuel ratio corrections calculated by the Twin Scan unit into the PC Link Tuner software. Twin Tuner II units also allow for ignition timing adjustment.