The computer in your 99-03 7.3L Powerstroke Diesel equipped vehicle will turn on the "Service Engine Soon" light at about 24psi of boost (some calibrations may come on at lower pressures)...a pressure easily attained by todays high performance chips, tuners and modules. At the same time, the computer will reduce fueling (power) in an effort to bring the boost pressure down. This reduced power mode will remain in effect until the PCM sees enough continuous operation without the fault (usually a few minutes of driving), the ignition is cylced or the code that tripped the SES light is cleared electronically. Our easy to install "Overboost Annihilator " kit will prevent the computer from setting the SES light and defueling the engine FOR AN OVERBOOST CONDITION (the light may still light for other reasons)...maintaining full power at ALL boost levels. This kit is pre-set to show your MAP sensor a maximum of 22-23psi. Features of the Driven Diesel "Overboost" Kit: •Completely Pre-Assembled and Permanently Pre-Set •High Quality Fixed-Pressure Industrial Pressure Regulator •Custom Stainless Steel Pre-Installed Mounting Bracket •High Quality Parker Push-Lok Fittings and Goodyear Hose •100% Accurate MAP Readings (up to pre-set max pressure) •100% Accurate Boost Gauge Readings (Mechanical Boost Gauges Only) ** devices that read/display boost from the MAP sensor will stop at the pre-set max of the Overboost Annihilator ** •ABSOLUTELY NO LOSS OF BOOST PRESSURE!!!!!