SKU: 50003-M40LF | UPC: 4957266720417
HKS SUPER FIRE RACING M40LF Spark Plug 2002-2021 Subaru Impreza WRX STI
The HKS Super Fire Racing M40LF delivers reliable ignition for 2002-2021 Subaru Impreza WRX and STI models. This iridium plug ignites fuel mixtures more effectively in turbocharged EJ20 and EJ25 engines for increased horsepower and throttle response. Built for racing it withstands high boost and RPM demands.
Key Features
- 0.4mm Iridium Center Electrode: Creates focused spark for complete combustion at high engine speeds
- Platinum Flat Pad Ground Electrode: Reduces electrode wear extends plug life under racing conditions
- Heat Range 40: Handles extreme heat from turbo setups prevents pre-ignition
- High-Strength Ceramic Insulator: Resists flashover ensures consistent performance in wet or dirty environments
- Nickel-Plated Shell: Thread M14x1.25 reach 26.5mm hex 16mm promotes heat dissipation fights corrosion
Product Notes
- Sold as single plug full set of 4 required for WRX 6 for STI
- Factory gap 0.8mm adjust to 0.75-0.85mm based on engine tune
- Packaged in protective plastic case for safe handling
Installation Notes
- Professional installation recommended.
- Torque to 18-21 ft-lbs using anti-seize on threads
- Direct OEM replacement works with factory ignition coils
This Part Fits
| Year | Make | Model | Submodel |
|---|---|---|---|
| 2002-2007 | Subaru | Impreza | WRX |
| 2004-2007 | Subaru | Impreza | WRX STI |
| 2008-2014 | Subaru | Impreza | WRX |
| 2008-2021 | Subaru | Impreza | WRX STI |
| 2004-2009 | Subaru | Impreza | WRX TR |
Why Choose HKS?
- 45 years leading JDM performance parts for Subaru enthusiasts
- Japanese manufacturing delivers exact tolerances for EJ engines
- Tested in Super GT and rally for real-world track results
Frequently Asked Questions
- Q: Will this plug fit my 2010 STI hatchback?
A: Yes it matches all 2002-2021 Impreza WRX STI sedan hatch wagon with EJ25 turbo engines - Q: What electrode materials improve longevity?
A: 0.4mm pure iridium center and platinum ground pads resist spark erosion last 2x longer than copper - Q: Does HKS provide warranty support?
A: Limited manufacturer defect warranty contact retailer for claims with proof of purchase
Shipping & Handling
- Method: UPS Ground or USPS Priority
- Availability: In stock – ships same or next business day
- Packaging: Individual plastic case in 4 x 1 x 1 inch box
- Weight: 1.6 oz shipping weight
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