SKU: 50003-M45IL-1
HKS SUPER FIRE RACING M45iL Spark Plug – Single for Subaru Impreza WRX STI 2004-2021 Legacy GT 2005-2009
HKS Super Fire Racing M45iL is a single iridium spark plug engineered for high-revving performance engines. It fits Subaru Impreza WRX STI Forester XT Legacy GT Nissan 350Z G35 Mazda RX-8 and more delivering sharper ignition for improved throttle response combustion efficiency and horsepower. Replace worn plugs to restore peak engine performance and reliability in turbocharged setups.
Key Features
- 0.8mm Pure Iridium Tip: Provides focused spark concentration for reliable ignition even at 10,000+ RPM reducing misfires in demanding racing conditions.
- 45mm Reach 14mm Thread: Exact OEM-spec dimensions ensure drop-in compatibility with gasket seat design for secure seal and heat dissipation.
- V-Grooved Ground Electrode: Creates air turbulence around the spark improving flame kernel growth for fuller combustion and power output.
- Projected Insulator: Resists carbon fouling and maintains consistent heat range during extended track sessions.
- High Thermal Conductivity: Pure iridium alloy withstands extreme cylinder temperatures for longer lifespan versus copper or platinum plugs.
Product Notes
- Sold as single plug. Order quantity needed for full engine set (4 or 6 depending on model).
- Pre-gapped to 0.8mm. Verify and adjust if necessary before installation.
- Store in original packaging to protect fine tip from damage.
Installation Notes
- Professional installation recommended.
- Torque to 18-22 ft-lbs using thin-wall deep socket to avoid insulator damage.
- Apply anti-seize compound to threads. Compatible with stock coils and wiring.
This Part Fits
| Year | Make | Model | Submodel |
|---|---|---|---|
| 2004-2021 | Subaru | Impreza | WRX STI 2.5L |
| 2008-2014 | Subaru | Impreza | WRX 2.5L |
| 2008-2012 | Subaru | Forester | XT 2.5L |
| 2005-2009 | Subaru | Legacy | GT 2.5L |
| 2005-2009 | Subaru | Outback | XT 2.5L |
| 2003-2008 | Nissan | 350Z | 3.5L V6 |
| 2003-2007 | Nissan | G35 | 3.5L V6 |
| 2004-2011 | Mazda | RX-8 | 1.3L Rotary |
| 2003-2005 | Mitsubishi | Lancer Evolution | Evo 8 2.0L |
| 2006-2007 | Mitsubishi | Lancer Evolution | Evo 9 2.0L |
Why Choose HKS?
- 45+ years of motorsport development powers real-world track-proven components.
- Japanese manufacturing ensures tight tolerances and consistent quality.
- Engineered specifically for boosted and high-output engines like EJ25 and VQ35.
Frequently Asked Questions
- Q: Will this fit my 2008+ Subaru WRX STI?
A: Yes it directly replaces OEM plug in all 2.5L EJ25 turbo models from 2004-2021 with 14mm x 45mm specs. - Q: What material is the center electrode?
A: 99.9% pure iridium alloy with 0.8mm diameter for superior durability and spark focus versus standard nickel plugs. - Q: What is the warranty and gap setting?
A: HKS offers limited warranty against defects. Ships pre-gapped at 0.8mm suitable for most performance tunes.
Shipping & Handling
- Method: UPS Ground or USPS Priority
- Availability: In stock – ships same or next business day
- Packaging: Compact retail box 4 x 3 x 1.5 inches
- Weight: 0.11 lbs
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