Performance Spark Plugs

The best spark plugs for your build are iridium plugs in the correct heat range for your tune: stock heat range for a stock or lightly modified car, and one step colder for higher boost. NGK Laser Iridium plugs cover common applications like the 15-21 WRX, the 14-16 Forester XT, the 16-20 Honda Civic 1.5T, and the 09-17 Nissan GT-R, and a proper gap tool keeps the electrode gap consistent across all cylinders. Always gap to your tuner's spec, and check your year and model before ordering.

Spark plugs ignite the air-fuel mixture, and the heat range controls how quickly the plug sheds heat into the cylinder head. Too hot a range on a boosted engine risks pre-ignition; too cold a range on a stock engine can foul. Iridium's fine-wire electrode needs less voltage to fire and lasts far longer than copper, which is why it is the default for modern turbo engines. When shopping, match the thread size, reach, and heat range to your engine, and gap carefully.

NGK is a Japanese ignition specialist and one of the world's largest spark plug manufacturers, supplying original equipment plugs to automakers and a deep aftermarket catalog. Its Laser Iridium line uses a laser-welded iridium center electrode paired with a platinum ground pad for long service life, and its heat-range numbering lets tuners step colder as boost rises. This collection includes NGK stock-heat-range plugs for the 15-21 WRX and 14-16 FXT, heat range 7 iridium plugs covering 06-15 WRX, 04-15 STI, 05-08 Legacy GT, and the 2.0L Genesis Coupe, a Laser Iridium plug for the 2016-2020 Honda Civic 1.5T, and GT-R fitments.

Torque Solution supports the ignition side of the garage with precision tools: this collection carries its 14mm spark plug gap tools, including a version with a built-in feeler gauge, for setting electrode gaps without damaging fine-wire iridium tips. Gap tools are the often-skipped companion purchase that makes a plug swap actually correct.

See Ignition Systems for coils and related ignition upgrades, and Torque Solution for the brand's full catalog. Pair fresh plugs with a healthy fuel system via Fuel Systems and Fuel Injector Clinic. Shop bestsellers like the NGK Laser Iridium plugs for 15-21 WRX and 14-16 FXT, the NGK heat range 7 iridium set, and the Torque Solution gap tool with feeler gauge. Read A Guide to Subaru Engine Modifications for the full picture.

What heat range do I need?

Stock heat range works for stock or lightly modified cars. If you are running more boost or an aggressive tune, step one range colder and ask your tuner for the right plug.

Do I need to gap iridium plugs?

Yes. Always verify and set the gap with a proper gap tool, and never pry against the iridium center electrode.

How often should I replace spark plugs?

Iridium plugs typically last much longer than copper plugs. Follow your owner's manual service interval, and inspect sooner on tuned or tracked cars.

Will new plugs fix a misfire?

Only if worn plugs are the cause. If a misfire persists with fresh, correctly gapped plugs, check the ignition coils and fuel system next.