SKU: 50003-M40G | UPC: 4957266720301 HKS Super Fire Racing M40G Spark Plug 2002-2021 Subaru Impreza WRX STI Forester Legacy HKS Super Fire Racing M40G delivers high-performance ignition for turbocharged Subaru EJ20 EJ25 engines. It fits 2002-2021 Impreza WRX STI Forester XT Legacy GT Outback XT models. Stronger spark improves combustion efficiency throttle response and power under high boost RPM. Key Features Fine wire center electrode: Promotes stable ignition kernel growth for complete fuel burn and consistent power delivery Racing heat range 40: Resists fouling and handles extreme cylinder temperatures in boosted applications Nickel alloy construction: Provides extended service life in competition environments with repeated heat cycles Large ground electrode design: Shields flame kernel to prevent pre-ignition damage while maintaining spark focus Pre-gapped specification: Ensures drop-in compatibility with OEM specs for Subaru EJ20 EJ25 turbo engines Product Notes Sold as single plug order quantity needed for full set replacement Use anti-seize on threads during installation to prevent galling Ships in protective foam insert box dimensions 3.5 x 1 x 1 inches Installation Notes Professional installation recommended. Torque to 18-22 ft-lbs using thin wall socket to avoid cracking porcelain Compatible with OEM coil packs and wiring no adapters required This Part Fits Year Make Model Submodel 2002-2007 Subaru Impreza WRX 2004-2007 Subaru Impreza WRX STI 2004-2013 Subaru Forester XT 2005-2009 Subaru Legacy 2.5 GT 2005-2009 Subaru Outback XT 2008-2014 Subaru Impreza WRX STI 2015-2021 Subaru WRX STI All Why Choose HKS? HKS pioneered JDM tuning since 1973 with motorsport-proven components Plugs tested in endurance racing for reliability under extreme conditions Precision-machined in Japan for exact OEM thread fit and gap accuracy Frequently Asked Questions Q: Does this fit 2004-2007 Subaru STI EJ25 turbo? A: Yes direct replacement for OEM plugs in all EJ25 turbo Impreza STI models from 2004-2007 Q: What material is the electrode made from? A: Racing-grade nickel alloy center wire and ground strap for heat resistance and anti-fouling properties Q: What is the warranty and gap spec? A: 1-year manufacturer warranty pre-gapped to 0.8-0.9mm verify with gap tool before final torque Shipping & Handling Method: UPS Ground or USPS Priority Availability: In stock – ships same or next business day Packaging: Compact cardboard box with foam insert 3.5 x 1 x 1 inches Weight: 0.1 lb Reviews There are no reviews yet. Be the first to review “HKS SUPER FIRE RACING M40G” 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.
