• Manley Extreme Duty Stainless Valves | Subaru WRX (EJ20) / 2004 STi (11139-8)
  • Manley Extreme Duty Stainless Valves | Subaru WRX (EJ20) / 2004 STi (11139-8)
  • Manley Extreme Duty Stainless Valves | Subaru WRX (EJ20) / 2004 STi (11139-8)
  • Manley Extreme Duty Stainless Valves | Subaru WRX (EJ20) / 2004 STi (11139-8)
  • Manley Extreme Duty Stainless Valves | Subaru WRX (EJ20) / 2004 STi (11139-8)
  • Manley Extreme Duty Stainless Valves | Subaru WRX (EJ20) / 2004 STi (11139-8)
1 6

Manley Extreme Duty Stainless Valves | Subaru WRX (EJ20) / 2004 STi (11139-8)

Manley Extreme Duty Stainless Valves | Subaru WRX (EJ20) / 2004 STi (11139-8)

11139-8

In stock

$506.87 USD
$652.79 USD $506.87 USD
ADDITIONAL DISCOUNTS APPLIED AT CHECKOUT Sold out

The Manley 00-03 Subaru WRX (EJ20) / 04 STi Exhaust 33mm Stainless Extreme Duty Valves are high-performance engine components designed to withstand extreme conditions. Crafted from durable stainless steel, these valves are engineered for maximum strength and longevity, making them suitable for demanding applications such as top-tier racing and high-performance builds. Their design ensures reliable sealing and efficient airflow, contributing to enhanced engine power and responsiveness. Built to meet the rigorous standards of professional motorsports, these valves deliver superior durability and consistent performance under extreme stress.

These valves are specifically designed for Subaru WRX models from 2000 to 2003 and 2004 STi variants, fitting the EJ20 engine. They serve as direct replacements or upgrades for stock valves, ideal for street, track, or racing applications where durability and performance are critical. Installation involves standard valve replacement procedures, and the kit includes the necessary valves for a complete upgrade. Suitable for enthusiasts seeking to improve engine efficiency and power output, these stainless steel valves are a reliable choice for high-performance Subaru builds.

Overview

Manley Performance Manley 00-03 Subaru WRX (EJ20) / 04 STi Exhaust 33mm Stainless Extreme Duty Valves

Fitment Summary

Part #: 11139-8

Overview

The Manley Extreme Duty Series Valves are high-performance engine components designed to withstand the rigorous demands of racing and high-stress applications. Crafted from premium stainless steel, these valves are engineered for durability, heat resistance, and consistent performance under extreme conditions. They are ideal for enthusiasts and professional racers seeking to optimize their Subaru WRX and STI engines, especially in high-performance or modified setups. With their robust construction, these valves help maintain proper airflow, improve combustion efficiency, and support the engine’s overall reliability during demanding driving scenarios.

Key Features

Designed with precision and durability in mind, these valves feature:
  • Constructed from high-quality stainless steel for corrosion resistance and strength
  • Engineered to handle high temperatures and aggressive valve timing
  • 33mm valve diameter optimized for performance applications
  • Extreme duty design suitable for racing and high-stress environments
  • Precision-machined for perfect fit and sealing
  • Designed to support high RPM operation and aggressive cam profiles

Construction & Design

These valves are manufactured from stainless steel, offering excellent durability and heat resistance. The precise machining ensures optimal sealing and consistent performance, making them suitable for high-performance engine builds.

Driving Feel & Feedback

While primarily a performance upgrade, these valves contribute to smoother engine response and reliable operation at high RPMs, supporting a more engaged driving experience.

Installation & Fitment

Installation requires proper engine disassembly and precise fitting, typically performed by experienced technicians or enthusiasts familiar with Subaru engine modifications.

What’s Included

The package includes a set of stainless steel valves designed specifically for Subaru WRX (EJ20) models from 2000 to 2003 and 2004 STI models with a 33mm valve diameter, suitable for extreme duty applications.
View full details