Manley Performance Extreme Duty Stainless Steel Exhaust Valves +1mm Oversized - 2002-2005 Subaru WRX / 2004-2021 STI
Manley Performance Extreme Duty Stainless Steel Exhaust Valves +1mm Oversized - 2002-2005 Subaru WRX / 2004-2021 STI
Manley Performance
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Every product is sourced from authorized manufacturers or distributors. If something isn’t right with fitment or condition, we’ll work with you to resolve it fairly.
NO GUESSWORK,
JUST PARTS THAT WORK.
Let’s finish that car.
PRODUCT DETAILS
Okay you’re in the middle of a motor rebuild and so far you have all your ducks in a row. You’ve got big turbo, forged pistons, flat bill hat, energy drink, oh yeah, VALVES! The Manley Race Series Valves, and Extreme Duty Valves have been designed to make sure your head is moving air effectively so that your engine is using power to its fullest potential.
The exhaust valves have been crafted from a XH-426 stainless exhaust material, and the intake valves have been crafted from NK-842 stainless steel.These valves also feature chrome stems, as well as hard tips, and the design will provide improved flow with the “Pro Flo” underhead.
The valves are finished off with a fully machined, swirl polished finish, and come with a 33mm head diameter.
WHY WE CARRY THIS
We only list parts we’d run ourselves or recommend to a friend building a real car. If it feels vague, unverified, or inconsistent, it doesn’t make the cut.
- Fitment-first mindset — no “universal” roulette
- Brand reputation matters — we favor proven manufacturing
- Support that actually responds with real answers
WHAT TO EXPECT
This is the clean path: correct fitment, clean install, and results that match the intent.
- Install-ready experience with correct mounting where provided
- Finish that holds up to real driving, not just photos
- Selections on this page drive the exact fitment shipped
TRUST, BUILT INTO THE PROCESS.
Anyone can list parts. We curate what belongs on a serious build. Our goal is simple: fewer surprises, cleaner installs, and confidence when you hit “Buy.”
Fitment checked
We prioritize vehicle-specific listings and clear selection logic so you’re not gambling on compatibility.
Brand discipline
Proven manufacturing and consistent quality matter more than hype. We bias toward what actually holds up.
Real support
If you have a question, you’ll get a human answer that helps you finish the build — not a copy-paste shrug.
Okay you’re in the middle of a motor rebuild and so far you have all your ducks in a row. You’ve got big turbo, forged pistons, flat bill hat, energy drink, oh yeah, VALVES! The Manley Race Series Valves, and Extreme Duty Valves have been designed to make sure your head is moving air effectively so that your engine is using power to its fullest potential.
The exhaust valves have been crafted from a XH-426 stainless exhaust material, and the intake valves have been crafted from NK-842 stainless steel.These valves also feature chrome stems, as well as hard tips, and the design will provide improved flow with the “Pro Flo” underhead.
The valves are finished off with a fully machined, swirl polished finish, and come with a 33mm head diameter.
