HKS SUPER FIRE RACING M40 HKS HKS50003-M40
HKS SUPER FIRE RACING M40 HKS HKS50003-M40
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HKS SUPER FIRE RACING M40

HKS
HKS50003-M40
4957266720219
Spark Plugs
16 Units In Stock - Ships Next Business Day
$ 270.00
FREE Ground Shipping!
$ 270.00

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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