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 Reviews There are no reviews yet. Be the first to review “HKS SUPER FIRE RACING M40” Cancel replyYour email address will not be published. Required fields are marked *Your rating * Rate… Perfect Good Average Not that bad Very poor Your review *Name * Email * Save my name, email, and website in this browser for the next time I comment.
