HKS SUPER FIRE RACING M40G

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