GSC 2013-8 +1mm Exhaust Valves for 02-14 WRX/04-21 STI EJ20/EJ257

Vehicle Fitment

• 2002-2014 Subaru Impreza WRX (EJ205/EJ255 turbo, AWD)
• 2004-2021 Subaru Impreza WRX STI / Subaru STI (EJ257/EJ207 turbo, AWD)
• Fits Subaru EJ-series turbo cylinder head applications using EJ205, EJ207, and EJ257 engines
• Compatible with 33mm +1mm oversize exhaust valve applications for Subaru EJ20/EJ25 turbo engines
• AWD applications confirmed; no FWD/RWD/4WD vehicle coverage verified
• Includes legacy GD/GG, GR/GV, and VA-chassis WRX/STI applications where EJ-series turbo heads apply
• Does not apply to FA20DIT, FA24, EZ-series, or naturally aspirated EJ cylinder heads without separate verification
• Fitment confirmed through 2021. 2022-2025 coverage unconfirmed at time of listing.

Features

• GSC Power-Division stainless steel exhaust valve set
• +1mm oversized exhaust valve design for increased flow potential
• 33mm exhaust valve head diameter
• Set of 8 valves for complete Subaru EJ-series exhaust side service
• Designed using advanced 3D simulation for improved strength and airflow
• Chrome-polished finish listed by trusted retailers
• Suitable for aggressive camshaft and higher-horsepower engine builds
• Performance valvetrain upgrade for rebuilt or ported cylinder heads
• Intended for EJ20/EJ25 turbo engine performance applications
• Compatible with proper machine work and valve-seat preparation

Specifications

• Part Number: 2013-8
• Brand: GSC Power-Division
• Product Type: Exhaust valve set
• Valve Quantity: 8
• Valve Head Diameter: 33mm
• Size: +1mm oversize
• Material: 23-8N stainless steel
• Position: Exhaust
• Engine Compatibility: Subaru EJ205 / EJ207 / EJ257
• Application: Performance cylinder head builds

Included Components

• 8x exhaust valves

Product Description

The GSC 2013-8 is a set of eight +1mm oversized exhaust valves for Subaru EJ-series turbo engines, covering confirmed EJ205, EJ207, and EJ257 applications used in 2002-2014 WRX and 2004-2021 STI models. Trusted Subaru performance retailers consistently identify this part as a 33mm exhaust valve set for EJ20/EJ25 turbo cylinder heads, making it a proper valvetrain upgrade for rebuilt, ported, or high-output cylinder head combinations.

This set uses 23-8N stainless steel construction and a +1mm oversize head to support improved exhaust-side flow in performance applications. Retailer references also describe these valves as being designed with advanced 3D simulation for a stronger, higher-flowing valve head, and as suitable for use with more aggressive camshafts and higher-horsepower builds. Because these are oversize exhaust valves, proper machining and valve-seat work should be expected before installation.

This product does not change vehicle ride height, so no front or rear lift/drop height applies. Fitment is limited to compatible Subaru EJ turbo cylinder heads and should not be assigned to FA20DIT, FA24, naturally aspirated EJ engines, or non-EJ Subaru platforms without separate confirmation.