GSC Power Division 3027-8 Manganese Bronze Exhaust Valve Guide Smooth Subaru EJ

Vehicle Fitment

• 2002-2014 Subaru Impreza WRX (EJ205, AWD)
• 2004-2021 Subaru Impreza WRX STI (EJ257 / EJ257B, AWD)
• 2005-2012 Subaru Legacy GT / Outback XT (EJ255, AWD)
• 2004-2013 Subaru Forester XT (EJ255, AWD)
• JDM 1999-2007 Subaru Impreza WRX STI (EJ207, AWD)

Fitment Notes

• Traditional smooth-style guide (no stopper) - seating depth must be measured and verified during installation; the stopper-style exhaust equivalent for this engine family is GSC 3025-8.
• Traditional smooth-style intake equivalent is GSC 3028-8.
• Fits EJ205, EJ207, EJ255, EJ257, and EJ257B engines - does not fit EJ20 SOHC or non-turbocharged EJ25 variants with different valve stem or guide boss specifications.
• Standard OD sizing; light honing of the guide boss may be required depending on head condition and target clearance specification.
• Oversized OD options (+0.001" and +0.003") are available individually for heads requiring bore service.

Features

• Manufactured from true C67410 Manganese Bronze for superior lubricity, heat dissipation, and long-term wear resistance over OEM cast iron guides.
• Traditional smooth profile for direct compatibility with standard EJ-series head configurations without modification.
• CNC-turned on dedicated precision turning centers to maintain the tightest OD-to-ID concentricity tolerances in the aftermarket.
• True-to-size OD minimizes guide boss honing on heads that don't require bore service, reducing overall installation time.
• Engineered to improve exhaust port airflow compared to the OEM guide profile design.
• Compatible with GSC EJ-series exhaust valves, valve stem seals, and spring kits for a complete matched valvetrain rebuild.

Specifications

• Position: Exhaust
• Style: Traditional Smooth (no stopper)
• Material: Manganese Bronze (proprietary C67410 blend)
• Total Length: 1.873" / 47.57mm
• Outer Diameter: 0.4357" / 11.07mm
• Valve Stem Diameter: 6mm
• Application: Subaru EJ205, EJ207, EJ255, EJ257, EJ257B

Included Components

• 8x GSC Power Division Manganese Bronze Traditional Exhaust Valve Guides (Standard OD)

Product Description

The GSC Power Division 3027-8 is a set of eight traditional smooth-style Manganese Bronze exhaust valve guides for Subaru's turbocharged EJ20 and EJ25 engine family, covering the EJ205, EJ207, EJ255, EJ257, and EJ257B across the WRX, WRX STI, Legacy GT, Outback XT, and Forester XT. The key distinction from the 3025-8 is the absence of a stopper collar - the 3027-8 uses a clean smooth profile throughout, which requires the installer to manually measure and verify seating depth during installation. This is the preferred choice for experienced builders who are already set up to check depth protrusion and want a traditional-style guide.

Made from true C67410 Manganese Bronze and CNC-turned to the tightest OD-to-ID concentricity tolerances available in the aftermarket, the 3027-8 delivers the same material performance advantages as the stopper-style variant - superior lubricity, heat transfer, and wear resistance over OEM cast iron - with minimal honing required on undamaged guide bosses. For heads requiring bore service, individually sold +0.001" and +0.003" oversized options are available. Builders who prefer a depth-controlled stopper-style installation should reference GSC 3025-8 instead.

A reliable foundation for any EJ-platform head build, the 3027-8 pairs directly with GSC's EJ-series exhaust valves, Viton valve stem seals, and beehive or conical spring kits for a complete and properly matched valvetrain on any WRX, STI, Legacy GT, Outback XT, or Forester XT.