SKU: 50003-M40 | UPC: 4957266720219
HKS Super Fire Racing M40 Spark Plug 2002-2021 Subaru Impreza WRX STI Legacy GT Forester XT
HKS Super Fire Racing M40 is a high-performance iridium spark plug designed for racing and tuned applications. It fits 2002-2021 Subaru Impreza WRX STI Legacy GT Forester XT models with EJ20 EJ25 engines. Expect stronger ignition sparks for better combustion higher horsepower throttle response and extended plug life under boost.
Key Features
- 0.7mm Pure Iridium Center Electrode: Produces focused spark for consistent ignition in high-rpm boosted conditions
- U-Groove Platinum Ground Electrode: Enhances flame kernel growth reduces misfires increases combustion efficiency
- Taper-Cut Ground Electrode Arm: Minimizes quenching improves ignitability supports higher power output
- High-Heat-Resistant Ceramic Insulator: Handles extreme temperatures from turbocharged racing use
- Copper Core Center Shaft: Provides rapid heat dissipation prevents pre-ignition in tuned engines
Product Notes
- Sold as individual plug gap preset to 0.032 inches adjust for specific engine tune
- Use in high-boost or modified engines replace every 20k miles for peak performance
- Secure OEM-style packaging protects threads during shipping
Installation Notes
- Professional installation recommended.
- Torque to 18-22 ft-lbs anti-seize on threads
- Compatible with OEM coil packs no special hardware needed
This Part Fits
| Year | Make | Model | Submodel |
|---|---|---|---|
| 2004-2021 | Subaru | Impreza | WRX STI |
| 2002-2007 | Subaru | Impreza | WRX |
| 2008-2014 | Subaru | Impreza | WRX |
| 2005-2009 | Subaru | Legacy | 2.5 GT |
| 2004-2013 | Subaru | Forester | XT |
| 2015-2021 | Subaru | WRX | STI |
Why Choose HKS?
- Motorsport heritage from Japanese tuning leader
- Racing-proven design tested in Super GT D1GP
- Precision manufacturing with advanced materials
Frequently Asked Questions
- Q: Does HKS Super Fire Racing M40 fit my 2008 Subaru STI EJ257?
A: Yes direct replacement for stock plugs in all EJ25 turbo models 2004-2021 STI improves spark under 20+ psi boost - Q: What materials are used in this spark plug?
A: 0.7mm pure iridium center electrode platinum-tipped ground electrode high-alumina ceramic insulator for durability - Q: What is the warranty and gap spec?
A: 1-year defect warranty preset gap 0.032 inches verify with tune check every 5k miles
Shipping & Handling
- Method: UPS Ground or USPS Priority
- Availability: In stock – ships same or next business day
- Packaging: HKS branded box 4 x 2 x 1.5 inches
- Weight: 2 oz
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