We researched and compared the best spark plugs for the Subaru Impreza across multiple generations. Our evaluation is based on manufacturer specifications, published industry standards, and aggregated owner feedback from forums and verified purchasers. Whether you drive a WRX, STI, or naturally aspirated model, we have a recommendation for you.
| Photo | Product | Score | Buy |
|---|---|---|---|
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NGK Laser Iridium (ILKAR7B11) Top Pick Iridium tip, 0.044 in. gap, pre-gapped |
9.0 | 🛒 Check Price |
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Denso Iridium TT (IKH16TT) Best Value Twin-tip iridium, 0.044 in. gap, pre-gapped |
8.7 | 🛒 Check Price |
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NGK Iridium IX (BKR6EIX-11) Performance Pick Iridium IX series, 0.044 in. gap, pre-gapped |
8.4 | 🛒 Check Price |
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NGK V-Power (BKR6E-11) Budget Pick Copper core, V-groove center electrode, 0.044 in. gap |
7.8 | 🛒 Check Price |
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Denso Platinum TT (PKH16TT) Long Life Option Twin-tip platinum, 0.044 in. gap, pre-gapped |
8.1 | 🛒 Check Price |
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Autolite XP Iridium (XP5364) Alternative Iridium Iridium tipped, 0.044 in. gap, pre-gapped |
7.3 | 🛒 Check Price |
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Champion Copper Plus (RC12YC) Classic Choice Copper core, 0.044 in. gap, not pre-gapped |
7.0 | 🛒 Check Price |
1. NGK Laser Iridium (ILKAR7B11): Top Pick
NGK Laser Iridium plugs are widely regarded as the gold standard for Subaru engines. In our research, they matched OEM part numbers for the majority of Impreza models, including the WRX and STI. Owner feedback consistently highlights smooth idle and improved throttle response. The iridium tip resists wear, and the triple-gasket design ensures reliable sealing.
However, these plugs are more expensive than standard copper options. If you are on a tight budget or drive a high-mileage non-turbo Impreza that does not require iridium, you may get similar performance from a less costly plug. They are overkill for some naturally aspirated engines that do not demand extreme longevity.
- OEM-equivalent for many Subaru engines including EJ and FA series
- Fine iridium center electrode for consistent spark and long life
- Triple-gasket sealing prevents compression leaks
Pros: Direct fit for most Impreza models; Excellent longevity, often exceeding 60,000 miles per owner reports
Cons: Premium price compared to copper plugs
2. Denso Iridium TT (IKH16TT): Best Value
The Denso Iridium TT offers a compelling balance of performance and value. Its twin-tip technology requires less voltage for a stronger spark, which can improve cold-start reliability. Based on owner feedback, these plugs work well in naturally aspirated Impreza models and provide a noticeable improvement over standard plugs.
For heavily modified or high-boost engines, some users have reported the tips wearing faster than NGK equivalents. If you track your car or run aggressive tunes, you might prefer a more durable option. For daily driving, these are an excellent choice.
- Twin-tip design reduces voltage requirement and misfire risk
- Long life, up to 60,000 miles claimed
- Compatible with many Subaru engines including EJ25
Pros: Lower cost than NGK Laser Iridium; Improved ignitability in cold starts
Cons: Some owners report shorter lifespan in turbo applications
3. NGK Iridium IX (BKR6EIX-11): Performance Pick
NGK Iridium IX plugs are a favorite among enthusiasts who want a performance edge without breaking the bank. They offer a more focused spark than standard plugs, which can improve low-end torque and responsiveness. In our comparison, they are a solid middle-ground between OEM iridium and budget options.
The trade-off is reduced service life. Many owners report needing to replace them around 30,000 miles, especially in turbo applications. If you prefer a set-and-forget solution, the Laser Iridium is a better long-term investment. These are ideal for those who enjoy periodic maintenance and want peak performance.
- Fine wire center electrode for concentrated spark
- Popular for performance builds and mild tunes
- Trivalent metal plating for anti-corrosion and anti-seize
Pros: Sharp throttle response and improved combustion; Affordable upgrade over copper plugs
Cons: Shorter lifespan than Laser Iridium, around 30,000-40,000 miles
4. NGK V-Power (BKR6E-11): Budget Pick
NGK V-Power plugs are the go-to budget option for older Impreza models, especially the 2.5L naturally aspirated engines. They provide reliable ignition at a fraction of the cost of iridium plugs. For a daily driver that sees moderate use, they are a practical choice.
Their main drawback is short service life. Owners report needing to change them every 15,000-20,000 miles to maintain performance. They are also not recommended for turbocharged engines, where the heat range and electrode durability are insufficient. If you own a WRX or STI, skip these.
- Standard copper spark plug for older Impreza models
- V-groove design improves flame propagation
- Very low cost per plug
Pros: Extremely affordable; Works well in non-turbo, low-compression engines
Cons: Short lifespan, typically 15,000-20,000 miles; Not suitable for turbo or high-performance engines
5. Denso Platinum TT (PKH16TT): Long Life Option
Denso Platinum TT plugs are designed for longevity. The platinum twin-tip construction resists wear better than copper, making them a good fit for owners who want to extend change intervals. In our research, they are a reliable choice for naturally aspirated Impreza models.
However, they do not offer the same ignitability as iridium plugs, and some owners in colder regions have reported occasional misfires during winter starts. If you live in a cold climate or have a turbo engine, an iridium plug may be more reliable. These are best for mild climates and non-performance driving.
- Platinum twin-tip design for extended life
- Lower voltage requirement for reduced coil stress
- Good for daily drivers seeking long intervals
Pros: Long service life, up to 60,000 miles claimed; Smooth idle and consistent performance
Cons: Not as performance-oriented as iridium options; Some owners report misfires in cold climates
6. Autolite XP Iridium (XP5364): Alternative Iridium
Autolite XP Iridium plugs are a budget-friendly iridium alternative. They offer similar technology to NGK and Denso at a lower price point. For a stock Impreza, they can provide acceptable performance and a modest improvement over copper plugs.
However, owner reviews are inconsistent. Some report premature wear or misfires after 20,000 miles, and a few have noted that the thread length or heat range is not ideal for certain Subaru engines. We recommend double-checking compatibility with your specific model year. If you want guaranteed fit and long life, stick with NGK or Denso.
- Fine wire iridium for consistent spark
- Compatible with some Subaru engines
- More affordable than NGK iridium
Pros: Lower price than NGK equivalents; Decent performance for daily driving
Cons: Mixed owner feedback on longevity; Fitment issues reported on some Impreza models
7. Champion Copper Plus (RC12YC): Classic Choice
Champion Copper Plus plugs are a classic design that has been around for decades. They can be used in older Impreza models with high mileage where cost is the primary concern. They are easy to gap and install, making them a viable temporary solution.
For any modern Impreza (2005 and newer), we do not recommend these plugs. They lack the heat range and durability needed for today’s engines, and owner reports indicate frequent misfires and rough idle. If you have a pre-2000 Impreza, they might suffice, but for best results, choose an iridium or platinum plug.
- Traditional copper plug for older engines
- Widely available and very inexpensive
- Works in a pinch for emergency replacement
Pros: Extremely low cost; Simple construction, easy to gap
Cons: Short lifespan, typically 10,000-15,000 miles; Not recommended for modern Subaru engines; may cause misfires
Frequently Asked Questions
What spark plugs are recommended for Subaru Impreza WRX/STI?
For turbocharged WRX and STI models, we recommend NGK Laser Iridium (ILKAR7B11) or Denso Iridium TT. These plugs handle higher cylinder pressures and temperatures better than standard plugs. Always use OEM-specified heat ranges and gap settings.
How often should I change spark plugs on my Subaru Impreza?
Service intervals vary by plug type. Copper plugs typically last 15,000-20,000 miles, platinum around 30,000-40,000, and iridium can go 60,000 miles or more. Refer to your owner’s manual, but many owners replace iridium plugs at 60,000 miles as preventive maintenance.
Can I use non-OEM spark plugs in my Impreza?
Yes, as long as they meet the same specifications (heat range, thread size, reach, and gap). Many aftermarket plugs like NGK and Denso are OEM for Subaru. Avoid cheap off-brands that may not have proper heat range or durability.
What happens if I use the wrong spark plug?
Using the wrong heat range or gap can cause misfires, poor fuel economy, or engine damage. Too hot a plug can cause pre-ignition; too cold can foul. Always verify compatibility using a reliable fitment guide or your vehicle’s service manual.
Do I need to gap spark plugs before installation?
Many premium plugs come pre-gapped, but it is good practice to check the gap with a feeler gauge. For Subaru Impreza, the standard gap is typically 0.044 inches. Adjust carefully if needed, as forcing the electrode can damage the plug.
Our Verdict
After researching and comparing specifications and owner feedback, our top pick for most Subaru Impreza owners is the NGK Laser Iridium (ILKAR7B11) due to its OEM fitment, longevity, and consistent performance. For those seeking excellent value, the Denso Iridium TT (IKH16TT) offers near-identical performance at a lower cost. Choose based on your engine type and budget.
