DUAL EXHAUST WITH 2 POST O2 SENSORS REQUIRES 2 UNITS. * EXISTING SENSOR MUST BE IN MINT CONDITION. NO O2 SENSOR INCLUDED. Looking for warranted less consumption without any hassle of installation of difficult apocryphal technical gadgets? Ecomaster warrants dramatic reduction of consumption by an average of 15 % w/o any compromise with engine performance. GAS MILEAGE BOOST IS OVER 12% on highways. You don't lose horsepower at the wheels or have to drive slowly & thriftily. State-of-the-art ECOMASTER PRO is an affordable fuel saver that gives you the mileage boost you are looking for! THE CHIP WIRES IN LINE w/ FACTORY POST OXYGEN SENSOR'S SIGNAL WIRE plus supplied by 12V. Chip is maximizing the Air Fuel Ratio (AFR) indicating fuel rich status in those circumstances when O2 sensor is sensing idle speed, low/medium engine load or while driving is nearly constant without extreme accelerations. When throttling suddenly, so acceleration is essential, the unit will return to factory mode with no delay & the engine is actuated promptly because O2 sensor will the ECU factory signal until acceleration keeps on. Tests on fuel economy have given an increase of 3-7 MPG depending on engine size, terrains, tire size etc. Even people who are not technical minded will find, chip is not difficult to install just needs 20 minutes. It will not affect engine reliability & durability. Stop wasting your money on high fuel prices today. Ecomaster pays for itself in no time at all. Units are sorted into several categories according to the type and operating range of vehicle's O2 sensor. Magnum Tuning has been applied the latest test-proven techniques and innovative designs since 1994 to improve upon fuel efficiency. Magnum Tuning has been dealing with manufacture of upgrades and fuel savers since 1994. Magnum's experience warrants peak fuel efficiency, reliability & perfect style. Magnum Parts are made in Europe & covered by 10-YEAR WARRANTY.