Manley Extreme Duty Exhaust Valves - 32mm Stainless | 2000-2003 Subaru WRX EJ20 / 2004 STi | Set of 8 (11137-8)

Build a bulletproof EJ20 top end with Manley Extreme Duty exhaust valves. The 11137-8 is a set of eight 32mm stainless exhaust valves engineered specifically for the 2000-2003 Subaru WRX EJ20 and 2004 STi — using Manley's XH-432 XtremeAlloy stainless material with chrome stems and hard tips to deliver exceptional heat resistance, wear resistance, and longevity in high-performance and high-boost EJ applications where factory valves are a known weak point.

Note: Set of 8 exhaust valves — covers all four cylinders of the EJ20. Verify head machining requirements (seat cutting, guide sizing) with your engine builder before ordering. Professional engine building required for installation.

Key Features:

• Manley Extreme Duty exhaust valve set — 8 valves
• 32mm head diameter
• XH-432 XtremeAlloy stainless steel construction
• Chrome stems for exceptional wear resistance
• Hard tips for durability at the valve stem tip contact point
• Swirl polished under-head areas for improved airflow
• Fully machined combustion faces for improved combustion efficiency
• Direct application for 2000-2003 Subaru WRX EJ20 and 2004 STi
• 1.1 lbs (set of 8)

Performance Benefits:

• XH-432 XtremeAlloy: Manley's premium exhaust valve alloy, engineered for extreme heat and force resistance — the same material used in Top Fuel, Funny Car, and marine engine applications where exhaust valve temperatures and loads far exceed those of even the most aggressive street and track builds
• Chrome Stems: Hard chrome plating on the valve stems provides exceptional wear resistance at the valve guide interface, maintaining precise valve-to-guide clearance over extended high-performance use and reducing the risk of guide wear that can lead to oil consumption and valve sealing issues
• Hard Tips: Hardened valve stem tips resist wear at the rocker arm or follower contact point, maintaining correct valve lash and preventing the tip wear that can cause valve lash to increase over time
• Swirl Polished Under-Head: The under-head area of each valve is swirl polished to reduce flow resistance and improve exhaust gas flow past the valve head, contributing to improved cylinder scavenging and volumetric efficiency
• Machined Combustion Faces: Fully machined combustion faces provide a precise, consistent sealing surface against the valve seat, improving combustion efficiency and reducing the risk of hot spots or uneven sealing that can lead to valve burning
• Extreme Duty Rating: Designed for applications where standard performance valves are insufficient — high-boost EJ builds, sustained high-RPM use, and applications with aggressive camshaft profiles that place high loads on the valve train

Specifications:

• Brand: Manley Performance
• Part Number: 11137-8
• Quantity: 8 valves (full exhaust set)
• Head Diameter: 32mm
• Material: XH-432 XtremeAlloy stainless steel
• Stem: Chrome
• Tip: Hard tip
• Finish: Swirl polished under-head, fully machined combustion face
• Application: 2000-2003 Subaru WRX EJ20 / 2004 Subaru WRX STi
• Weight: 1.1 lbs (set of 8)
• Barcode: 807298030845

Fitment Information:

• 2000-2003 Subaru WRX — EJ20 engine (GD/GG chassis)
• 2004 Subaru WRX STi — EJ20 engine
• Note: Exhaust valves only — intake valves sold separately
• Note: Professional engine building required — valve installation requires head machining (seat cutting to match valve), valve guide inspection/replacement, and precise assembly
• Note: Verify valve stem diameter and overall length compatibility with your specific head configuration before ordering — confirm with Manley or your engine builder
• Note: Head machining by a qualified engine builder is required to ensure correct valve-to-seat contact and sealing

What's Included:

• Manley Extreme Duty exhaust valves — set of 8 (11137-8)
• Note: Valve springs, retainers, locks, and seals not included — must be sourced separately for your specific build

Installation Notes:

• Professional engine building required
• Inspect and measure valve guides before installation — replace guides if worn beyond specification
• Cut valve seats to match the new valve's seat angle and width — do not install new valves on worn or uncut seats
• Measure installed valve height after seating to verify correct valve train geometry
• Select valve springs appropriate for your camshaft profile and intended RPM range
• Verify valve-to-piston clearance with your specific piston and camshaft combination before final assembly
• Lap valves to seats after machining for a final seal check

EJ20 Exhaust Valves — Why Upgrade:

The EJ20 engine in the 2000-2003 Subaru WRX and 2004 STi is a capable turbocharged platform, but its factory exhaust valves are designed for stock power levels and operating conditions. As EJ20 builds increase boost pressure, add aggressive camshafts, or are subjected to sustained high-RPM use, the factory exhaust valves become a limiting factor — they are exposed to higher exhaust gas temperatures, higher valve train loads, and more aggressive thermal cycling than they were designed to handle. The result can be valve burning, seat recession, guide wear, and ultimately valve failure — catastrophic outcomes in a high-performance engine build.

Manley's Extreme Duty exhaust valves address these limitations with the XH-432 XtremeAlloy material — a stainless steel alloy specifically developed for extreme exhaust valve applications. XH-432 provides significantly higher heat resistance than standard stainless valve materials, maintaining its mechanical properties at the elevated temperatures generated in high-boost, high-RPM EJ applications. The chrome stems and hard tips add wear resistance at the guide and rocker interfaces, ensuring the valve train maintains correct geometry over extended high-performance use.

Manley XH-432 XtremeAlloy — Material Overview:

XH-432 is Manley's proprietary exhaust valve alloy — a high-chromium, high-nickel stainless steel formulation developed for extreme temperature and force resistance. The alloy is used in Manley's most demanding exhaust valve applications, including Top Fuel and Funny Car drag racing engines where exhaust valve temperatures can exceed 1,500°F and valve train loads are extreme. For a high-boost EJ20 build, XH-432 represents significant overkill in terms of material capability — which is precisely the point. Using a material rated for the most extreme motorsport applications in a high-performance street or track EJ build provides a substantial safety margin that standard performance valve materials cannot match.

Why Manley Performance?

Manley Performance is one of the most respected names in performance engine components in North American motorsport, with decades of experience manufacturing connecting rods, pistons, valves, and valve train components for professional and amateur racing applications. Their valve range covers a wide spectrum from street performance to full race applications, and their Extreme Duty line represents the top of their valve offering — components designed for the most demanding applications in motorsport. For EJ20 engine builders who want the best available exhaust valve for a high-performance build, Manley's Extreme Duty line is a benchmark choice.

Perfect For:

• High-boost 2000-2003 Subaru WRX EJ20 and 2004 STi engine builds where factory exhaust valves are insufficient for the power level and operating conditions
• EJ20 builds with aggressive camshaft profiles requiring exhaust valves with superior heat and wear resistance
• Full engine rebuilds on high-mileage or previously overheated EJ20 engines where exhaust valve replacement is part of a comprehensive head rebuild
• Time attack, circuit racing, and sustained high-RPM EJ20 applications where exhaust valve durability is critical
• Engine builders wanting Manley's XH-432 XtremeAlloy exhaust valves for maximum reliability in a demanding EJ20 application

Perfect For: 2000-2003 Subaru WRX EJ20 and 2004 STi engine builders seeking Manley Extreme Duty 32mm stainless exhaust valves for superior heat resistance, wear resistance, and reliability in high-boost and high-performance applications.

Pro Tip: When specifying exhaust valves for a high-boost EJ20 build, discuss valve-to-seat contact width with your engine builder — a narrower seat contact width improves heat transfer from the valve to the seat (and thus to the head cooling system), which is critical for exhaust valve longevity in high-boost applications. A seat that is too wide retains heat in the valve head, accelerating valve burning. Your engine builder should cut seats to the correct width for your specific power level and intended use.

Extreme Duty | XH-432 XtremeAlloy | 32mm | Set of 8: 2000-2003 Subaru WRX EJ20 / 2004 STi. Professional engine building required. Seat cutting required. Intake valves sold separately. 1.1 lbs.

Build a reliable high-boost EJ20 with Manley 11137-8 Extreme Duty exhaust valves — XH-432 XtremeAlloy stainless, chrome stems, hard tips, 32mm, set of 8 for 2000-2003 Subaru WRX EJ20 and 2004 STi.