2004-2010 Subaru WRX/STI Ignition Coil

The basic requirements for a properly running engine are fuel, air, compression, and spark. Before increasing your engine's power, it's wise to ensure all maintenance is up-to-date and these processes are performing as intended. A weak spark from your ignition system can result in misfiring, rough idling, poor gas mileage, and damage to your catalytic converter, all of which hinder performance.