If you experience radio noise after installing the MSD Ignition, you may need to install an MSD Noise Filter. Electro Magnetic Interference (EMI) is occasionally generated from the MSD power cables and can be easily eliminated by installing the Noise Filter on the heavy power supply wires coming from the MSD. When the MSD draws current, it will draw through the Noise Filter instead of directly from the battery, so all other accessories that operate off 12 volts, like the radio, fuel pump, or the engine computer, will be unaffected by the MSD.The Noise Filter will also prevent damage to the MSD during jump-starts and will keep a vehicle's 12-volt line "clean" by removing any voltage and current surges that could interfere with the operation of some MSD accessories such as the Soft Touch Rev Control or the Two Step Module Selector. It is recommended that the Noise Filter be used on installations with the MSD 7 and 8 Series Igni­tions to prevent this interference.