Ignition Coil and Iridium Spark Plugs for Subaru WRX STI (2015-2021) 2.5L

High-Output Ignition Coil and Iridium Spark Plugs for 2015-2021 Subaru WRX STI

Direct OEM replacement ignition system designed to restore spark energy and eliminate misfires on tuned or aging EJ257 engines.

The Stock WRX STI Ignition Weakness

The factory ignition coils on the EJ257 degrade rapidly under high boost and thermal stress. As the VA chassis ages, coil packs often suffer from internal resistance breakdown and cracked epoxy housings due to persistent heat soak from the turbocharged boxer layout. This leads to weak spark propagation, hesitation during wide-open throttle, high-RPM misfires, and reduced fuel efficiency. Standard spark plug electrodes also erode faster in forced-induction environments, widening the plug gap over time and causing spark blowout under peak manifold pressure.

The Engineering Solution

This comprehensive kit provides four high-voltage ignition coils and four iridium-tipped spark plugs tailored for the 2.5L turbo engine. The ignition coils feature upgraded copper windings and high-dielectric epoxy resin to resist thermal breakdown and ensure consistent voltage output. Paired with iridium spark plugs, which utilize an ultra-fine center electrode for superior ignitability and a high melting point to withstand extreme combustion chamber temperatures, this setup guarantees a highly stable spark. The result is complete combustion, restored throttle response, and the elimination of boost-induced spark blowout.

Technical Specifications

Compatibility

• 2015 Subaru WRX STI 2.5L Turbo (EJ257)
• 2016 Subaru WRX STI 2.5L Turbo (EJ257)
• 2017 Subaru WRX STI 2.5L Turbo (EJ257)
• 2018 Subaru WRX STI 2.5L Turbo (EJ257)
• 2019 Subaru WRX STI 2.5L Turbo (EJ257)
• 2020 Subaru WRX STI 2.5L Turbo (EJ257)
• 2021 Subaru WRX STI 2.5L Turbo (EJ257)

The Subaru Standard

For high-performance JDM platforms like the VA STI, maintaining robust spark energy is critical for sustained power delivery and that signature boxer rumble. This ignition kit ensures reliable timing and maximum combustion efficiency under heavy loads.