10 Best Spark Plugs For WRX Reviewed by Experts – Best Spark Plugs For WRX.

When I first got my WRX, finding the right spark plugs felt like a puzzle. The FA20 and EJ25 engines rely heavily on clean, efficient combustion, especially if you’re running a tune. I’ve tested a variety of options, and choosing the best spark plugs for WRX models—whether you have the FA20 DIT or the older EJ25—is crucial for maintaining optimal WRX performance and longevity. This guide breaks down ten top contenders, helping you find the ideal replacement for better ignition and quicker response.

IMAGE	PRODUCT NAME	AMAZON LINK
	4 pc NGK Laser Iridium Spark Plugs compatible with Subaru…	View on Amazon
	NGK 96024 ILKAR8H6 Iridium Spark Plug, Pack of 4	View on Amazon
	A-Premium Iridium Platinum Spark Plugs Compatible with…	View on Amazon
	Genuine Subaru Iridium Spark Plugs 22401AA670 / SILFR6A for…	View on Amazon
	NGK (7913) SILFR6A Spark Plug – Pack of 4	View on Amazon
	NGK # 6418 Iridium Spark Plugs BKR6EIX – 4 PCS…	View on Amazon
	4 pc NGK Laser Iridium Spark Plugs compatible with Subaru…	View on Amazon
	4 pc NGK Iridium IX Spark Plugs compatible with Subaru…	View on Amazon
	PHILTOP Set of 4 Ignition Coil Pack and Iridium Spark…	View on Amazon
	OEM Genuine NGK Spark Plugs Kit for Subaru Impreza…	View on Amazon

4 pc NGK Laser Iridium Spark Plugs compatible with Subaru WRX 2.0L H4 2015-2020

These NGK Laser Iridium plugs are often considered the gold standard replacement for the FA20 WRX engine (2015-2020). Designed specifically for durability and precise ignition, they help maintain peak performance and excellent fuel economy right out of the box. If you want OEM quality with an emphasis on reliable, long-term sparking capabilities, these are a fantastic choice, especially if you’re running a stock or mild tune.

Key features that stand out:
– Genuine NGK Parts: Assurance of quality from the original equipment supplier.
– IMPROVE IGNITION AND SPARK EFFICIENCY: Advanced center and ground electrodes deliver strong combustion.
– REDUCE EMISSIONS AND MISFIRES: Promotes sharper spark focus for reliable operation.
– Corrosion Resistance: Durable shell ensures long-lasting functionality.

Pros:
– Excellent longevity and service life.
– Ideal heat range for stock or lightly modified FA20 engines.
– Proven reliability and high build quality.

Cons:
– Premium price compared to standard plugs.

Best for: Stock or mildly tuned 2015-2020 WRX owners seeking maximum durability and OEM-level performance.

Expert Opinion: NGK Laser Iridium plugs are known for their longevity and stability, making them a top recommendation for daily drivers who prioritize consistent performance and long replacement intervals over aggressive tuning changes.

NGK 96024 ILKAR8H6 Iridium Spark Plug, Pack of 4

The NGK 96024 plugs are another highly popular choice, specifically designed to meet or exceed OEM specifications for many modern turbocharged Subaru engines, including the FA20 WRX. These plugs offer the quality and reliability you expect from an OEM manufacturer, ensuring your engine runs smoothly. They strike a great balance between reliable ignition and robust construction.

Key features that stand out:
– Specified as Original Equipment: Often used by manufacturers for reliable performance.
– Quality, Reliability, and Durability: Built to strict OEM standards.
– World’s Largest Supplier: Confidence in component sourcing from NGK.

Pros:
– Direct OEM fitment for many WRX models.
– Excellent cold start and idling performance.
– Highly reliable under varied operating conditions.

Cons:
– May not be cold enough for extremely aggressive tunes.

Best for: OEM replacement for FA20 WRX owners who want genuine NGK quality without deviation from factory specs.

Expert Opinion: If you’re nervous about choosing the wrong plug, the 96024 is a safe bet. It offers factory performance and robustness, which is exactly what a stock turbo engine needs for health and reliability.

A-Premium Iridium Platinum Spark Plugs Compatible with Subaru Forester 2014-2018, WRX 2015-2020, 2.0L, Pack of 4

A-Premium offers a high-quality alternative that combines Iridium and Platinum materials, providing exceptional ignitability and longevity comparable to top brands like NGK. These plugs are a direct fit for the 2015-2020 WRX (2.0L turbocharged) and are designed to handle demanding engine environments. They are specifically engineered to offer long service intervals, reducing the frequency of replacement.

Key features that stand out:
– Exceptional Ignitability: Engineered alongside OEMs for maximum ignition performance.
– Iridium/Platinum Combination: Center electrode is Iridium; core material is Platinum, enhancing durability.
– Engineered for Longevity: Recommended replacement interval of 80,000 to 100,000 miles.

Pros:
– Excellent mileage lifespan due to dual precious metal construction.
– Competitive pricing compared to factory plugs.
– Precise OEM specifications (0.024 inch gap size).

Cons:
– Less established brand recognition than NGK among enthusiasts.

Best for: Budget-conscious FA20 WRX owners who need long service life and OEM compatibility.

Expert Opinion: Combining Iridium and Platinum is a solid engineering strategy for longevity. While perhaps not the first choice for highly boosted engines, these are perfect for reliable, high-mileage daily driving.

Genuine Subaru Iridium Spark Plugs 22401AA670 / SILFR6A for WRX & STi Legacy Forester Outback Impreza OEM Set of 4

When dealing with the EJ25 engine (found in older WRX and STi models), going Genuine Subaru is always a trusted path. These plugs are the exact component specified by the factory for various turbocharged Subaru models, including the WRX STI. Manufactured by NGK (part number SILFR6A), these plugs ensure seamless integration and guaranteed compatibility with your vehicle’s tune and ignition system.

Key features that stand out:
– Genuine Subaru Part: Guaranteed factory fitment and quality.
– NGK Laser Iridium Resistor: Utilizes reliable NGK technology (SILFR6A).
– Wide Turbo Fitment: Compatible with 2.5L Turbo Engines in many Subaru models (2012-2016 WRX, 2013-2019 WRX STI).

Pros:
– Guaranteed fitment and reliability for EJ25 turbo engines.
– Premium Laser Iridium construction.
– Eliminates guesswork on heat range for stock setups.

Cons:
– Can sometimes be priced higher due to Subaru branding.

Best for: WRX/STI owners with the 2.5L Turbo EJ engine who prioritize OEM quality and flawless compatibility above all else.

Expert Opinion: If you have an EJ-series engine and are running a factory or mild tune, just use these. They are the benchmark for reliability in that platform.

NGK (7913) SILFR6A Spark Plug – Pack of 4

This is the exact plug found inside the Genuine Subaru packaging (Product 4), just under the NGK brand name 7913. It is a Laser Iridium plug designed for the demanding requirements of the Subaru EJ25 turbo engine. Opting for the NGK-branded version can sometimes offer the same quality and direct fitment at a more accessible price point than the fully branded Subaru box. It’s a proven, direct replacement auto part.

Key features that stand out:
– Laser Iridium Construction: Offers superior lifespan and stable spark.
– Genuine NGK Parts: Reliable quality control.
– Direct Replacement: Matches OEM specifications for the EJ25T.

Pros:
– The industry standard plug for EJ25 turbo applications.
– Excellent ignition stability under boost.
– Often a better value than the Subaru-branded version.

Cons:
– Specifically focused on the EJ engine series, limiting compatibility with newer FA engines.

Best for: EJ25 WRX/STI owners who know they need the SILFR6A plug and want reliable NGK quality.

Expert Opinion: The 7913 is practically synonymous with reliable EJ25 performance. It’s what most tuners recommend for stock to stage 2 setups because of its consistent heat range and durability.

NGK # 6418 Iridium Spark Plugs BKR6EIX – 4 PCS NEW

The NGK Iridium IX line (6418 BKR6EIX) is incredibly popular among enthusiasts who are running performance setups that require a slightly different heat range or plug design than the OEM Laser Iridium. While typically gapped differently for certain applications, the Iridium IX offers a finer electrode for sharper, more focused ignition. These are great performance plugs, often used in older WRX models or custom builds.

Key features that stand out:
– NGK Iridium IX: Fine wire central electrode for maximum spark.
– Enhanced Ignition: Designed to improve throttle response and anti-fouling capabilities.
– Genuine NGK Parts: Reliable construction and quality.

Pros:
– Excellent choice for performance upgrades and custom tuning.
– Sharper spark helps improve idle and response.
– Highly resistant to carbon fouling.

Cons:
– Requires careful gapping adjustment for specific WRX models.

Best for: Older WRX models (pre-2008) or engines running mild performance tunes that benefit from the slightly different characteristics of the Iridium IX line.

Expert Opinion: Iridium IX plugs are often favored by tuners because they can handle moderate boost levels well. They don’t last as long as Laser Iridium, but they deliver a noticeable performance difference in certain tuned engines.

4 pc NGK Laser Iridium Spark Plugs compatible with Subaru WRX STI 2.5L H4 2013-2018

This specific kit is tailored directly for the later model WRX STI (2013-2018) with the 2.5L EJ engine. By specifically calling out the STI application, you are guaranteed the correct heat range and plug dimensions necessary for the higher-output engine. These Laser Iridium plugs offer the same long-life characteristics as other NGK precious metal plugs, ensuring your STI maintains its aggressive performance reliably.

Key features that stand out:
– Specific STI Fitment: Guaranteed compatibility for 2013-2018 STI 2.5L H4.
– Laser Iridium: Engineered for durability and high-heat environments.
– Direct Replacement: Ensures easy installation and maintenance.

Pros:
– Perfect OEM replacement for late-model EJ25 STI engines.
– Excellent resistance to detonation and pre-ignition.
– Long-lasting reliability even under high boost.

Cons:
– Premium cost reflects the high-performance application.

Best for: Owners of modern EJ25 WRX STI models who require the precise OEM plug for reliability and longevity.

Expert Opinion: For an STI, maintaining the correct heat range is non-negotiable. These specialized Laser Iridium plugs provide the necessary thermal control and performance required by the higher compression and boost of the EJ25.

4 pc NGK Iridium IX Spark Plugs compatible with Subaru WRX STI 2.5L H4 2013-2018

If you own a later-model STI and are leaning towards a performance-focused plug rather than the ultra-long-life Laser Iridium, the Iridium IX set for this application is a compelling option. While the Laser series is built for durability, the Iridium IX is known for its improved ignitability due to the fine wire electrode, often preferred by those running slightly aggressive street tunes where spark stability is key.

Key features that that stand out:
– Iridium IX Performance: Fine electrode design for enhanced ignition and response.
– STI Specific: Correct dimensions and heat range for 2013-2018 2.5L H4.
– Genuine NGK Quality: Trusted components for high-boost applications.

Pros:
– Improved throttle response and idle compared to worn-out OEM plugs.
– Excellent anti-fouling characteristics.
– Reliable choice for street-tuned STIs.

Cons:
– Shorter lifespan compared to the Laser Iridium versions (Product 7).

Best for: Tuned 2013-2018 WRX STI owners seeking a performance boost and don’t mind slightly shorter replacement intervals.

Expert Opinion: Choosing Iridium IX over Laser Iridium often comes down to budget and tuning level. For moderate tunes, the IX line offers great performance at a competitive price, but remember you’ll be doing the plug swap sooner.

PHILTOP Set of 4 Ignition Coil Pack and Iridium Spark Plugs Fits for Subaru 2010-2012 Legacy,2011-2013 Forester,2011-2014 Impreza,2015-2018 WRX STI

This product offers fantastic value by packaging both high-quality Iridium spark plugs and a matching set of ignition coil packs. This is a crucial consideration, especially if your WRX STI is high mileage or experiencing misfires that might be related to failing coils. The PHILTOP coils meet strict OE specs, ensuring stable high-voltage output, paired with reliable Iridium plugs for optimal engine health.

Key features that stand out:
– Complete Kit: Includes both ignition coils and Iridium spark plugs.
– High-Quality Coils: Features fast ignition within 0.1-0.2 seconds and protection against RF interference.
– Iridium Spark Plugs: Premium central electrode for enhanced performance and quick starts.
– Easy Installation: Designed for simple, safe fitment that matches or exceeds factory parts.

Pros:
– Excellent all-in-one maintenance solution.
– Solves potential misfires caused by aging coils/plugs simultaneously.
– Iridium plugs offer stability and durability (up to 3x life).

Cons:
– If only plugs are needed, this set is overkill and more expensive.

Best for: High-mileage 2015-2018 WRX STI owners performing major ignition system maintenance or chasing down persistent misfires.

Expert Opinion: Ignition coils often degrade unnoticed, especially in turbocharged cars. For preventative maintenance on older vehicles, replacing both plugs and coils simultaneously with an OE-compliant kit like this is highly recommended for stable engine operation.

OEM Genuine NGK Spark Plugs Kit for Subaru Impreza Outback Legacy Baja Forester SET OF 4

While focused on a broader range of older, non-turbo Subaru models, this OEM Genuine NGK kit (22401AA310) is important to include because some older WRX conversions or naturally aspirated (NA) swaps might require this specific heat range. These are quality, standard NGK plugs meant for reliable operation in non-turbocharged SOHC engines (1.8L, 2.2L, 2.5L) of the 1990s and early 2000s.

Key features that stand out:
– Genuine Subaru Part: Assures factory fitment for older platforms.
– OEM Standard: Ideal for maintaining factory performance in specified NA engines.
– Reliable NGK Construction: Trusted components for longevity.

Pros:
– Perfect replacement for early model, naturally aspirated Subaru platforms.
– Cost-effective for routine maintenance.
– High reliability in lower-stress engine environments.

Cons:
– Not suitable for any turbocharged WRX or STI engine due to incorrect heat range.

Best for: Owners of classic or non-turbo Subaru models (like the early 2.5L Impreza/Legacy) that might share chassis DNA with a WRX, but absolutely not for forced induction applications.

Expert Opinion: Always double-check your application. While this is a high-quality OEM plug, using it in a turbocharged WRX engine will lead to severe pre-ignition and engine damage. This is a maintenance plug, not a performance plug.

Comparison Short Insights

When choosing the best spark plugs for WRX, the most crucial factor is your engine type and whether it’s stock or tuned. The modern WRX (2015+) uses the FA20 DIT engine, while the older WRX/STI uses the EJ25.

For the FA20 DIT engine (2015+), your focus should be on plugs like the NGK 96024 or the 4 pc NGK Laser Iridium (Product 1). These plugs are designed for the high-temperature demands of direct injection. If you have a mild tune, the factory heat range plugs are usually sufficient and offer the longest lifespan.

The EJ25 Turbo engine (WRX STI) generally requires the NGK SILFR6A (7913), whether you buy the Genuine Subaru part (Product 4) or the NGK-branded one (Product 5). This plug provides the necessary thermal stability for the 2.5L turbo boxer.

If you are running an aggressive tune, you may need a colder heat range, often found in some specialty Iridium IX options (Product 8), but these should only be installed and gapped based on your tuner’s specific recommendations. Remember that Laser Iridium plugs are built for maximum longevity, while standard Iridium IX plugs often offer a sharper, more responsive spark at the cost of service life.

Final Verdict

Choosing the right WRX spark plug depends entirely on your needs: reliability, performance, or overall value.

If you own a Stock or Mildly Tuned FA20 WRX (2015+): The winner for reliability and longevity is the 4 pc NGK Laser Iridium Spark Plugs compatible with Subaru WRX 2.0L (Product 1). They offer exceptional service life, requiring fewer replacement cycles.

For owners of the EJ25 WRX/STI (2013-2018): For guaranteed factory performance and compatibility, stick with the Genuine Subaru Iridium Spark Plugs 22401AA670 / SILFR6A (Product 4). It is the proven choice for this platform.

Best Value for High-Mileage WRX STI: If you’re pushing high mileage and suspect ignition system weakness, the PHILTOP Set of 4 Ignition Coil Pack and Iridium Spark Plugs (Product 9) is the smart move, tackling two maintenance jobs at once.

FAQ: Choosing the Best Spark Plugs For WRX.

Q1: What is the recommended spark plug gap for a stock WRX FA20 engine?

For the FA20 DIT (2015+ WRX), the factory gap specification is generally tight, often around 0.024 inches (0.6 mm). It is crucial to confirm the exact measurement in your owner’s manual or on your current plug. If you are running a performance tune, your tuner may recommend reducing the gap slightly to prevent spark blowout under high boost.

Q2: Should I use a colder plug if my WRX is tuned or running high boost?

Yes, absolutely. A colder spark plug dissipates heat more quickly than a hotter plug. When you increase boost or horsepower in a WRX, the combustion chamber temperature rises significantly. Using a colder plug helps prevent pre-ignition and potential engine damage. Always consult your tuner before switching heat ranges.

Q3: How often should WRX spark plugs be replaced?

Replacement intervals vary depending on the plug type and engine use. Standard factory WRX Iridium or Laser Iridium plugs (like the NGK options) are typically rated for 60,000 to 80,000 miles in a stock setup. However, if your WRX is heavily modified or experiences frequent high-RPM use, you should consider replacing them every 15,000 to 30,000 miles to maintain peak WRX performance.

Q4: What is the main difference between Iridium IX and Laser Iridium plugs?

The key difference lies in the design purpose. Laser Iridium plugs are specifically designed for maximum durability and longevity, often utilizing both Iridium and Platinum electrodes for minimal gap erosion over a long life cycle. Iridium IX plugs feature a finer central electrode optimized for sharper ignitability and enhanced performance, but they are generally expected to have a shorter service life (though still much longer than standard copper plugs).

Q5: Can using the wrong spark plugs cause misfires in my WRX?

Yes. Using the incorrect spark plug heat range, a gap that is too wide or too narrow, or poor-quality components can all lead to persistent misfires, especially under acceleration and high boost. Misfires can lead to rough idling, reduced power, and eventually catalytic converter damage. Always ensure you match the plug specification (including heat range) to your Subaru WRX engine type and current tune.

Q6: Are NGK plugs always the best choice for a Subaru WRX?

NGK holds a dominant position because they are the OEM supplier for Subaru, meaning their plugs are engineered precisely to meet Subaru’s specific requirements for heat range and fitment. While other high-quality brands exist, NGK plugs, especially the NGK Laser Iridium and Iridium IX lines, offer the most reliable and guaranteed performance for most WRX turbo applications.