The S&S system makes use of crank position sensor, cam position sensor if present, MAP sensor, cylinder head temperature sensor and an exclusive knock sensor that detects detonation or knock while the engine runs. Knock sensor allows the ECU to automatically adjust ignition timing to eliminate knock whenever it occurs. Optimizes power and fuel economy. The Intelligent Spark Technology Ignition Module requires an installation kit that must be purchased separately. Optional high-output coil also available: designed for the S&S Variable Fuel Injection System, the single-fire coil is actually two separate coils in a single package; coil impedance 3 ohm per coil (sold separately). Made in the U.S.A.. Not for fuel-injected models.. Not recommended for kick start applications unless a cam position sensor is used. Engines using crankshaft position sensors will be difficult to kick start.. S&S IST ignition modules manufactured after 10-1-03 (serial number begins with "E" or higher letter) already contain software to support the Guardian Diagnostic System. These modules will work in all applications except 2004-05. Modules manufactured after 10-1-05 (serial number begins with "G" or higher letter) are compatible with 04-05 models in addition to the other specified applications..