MISHIMOTO Subaru WRX/STI Ignition Coil 2004-2010

A properly functioning engine depends on fuel, air, compression, and spark. Before increasing power output, it is essential to ensure all maintenance is current and each system is performing as intended. Weak spark delivery can lead to misfires, rough idle, reduced fuel economy, and catalytic‑converter damage, all of which diminish overall performance and drivability. Ensuring a strong, consistent ignition signal is a critical first step before pursuing further modifications.