Mishimoto 04-10 Subaru WRX/STI Ignition Coil - 4-PackThe 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. Mishimoto ignition coils aim to provide high quality