It plugs into your MAF and I believe you adjust the voltage/settings to match whatever injectors/induction you have on the car.
http://www.pro-flow.com/Instructions..._optimizer.htm
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Current Rides: 2001 BMW 540i, 2002 BMW 330i (wife's car)
Previous Rides: 2001 Saleen Mustang SC Speedster Convt, 95 Mustang GT w/ Built 331/Vortech S Trim - 550rwhp, 93 Mustang LX Procharged 400rwhp, 99 SVT Lightning 475RWHP