How to Choose the Right Header for Your Subaru: Equal Length vs. Unequal Length Explained

Introduction

If you've spent any time in the Subaru community, you've heard the debate: equal length (EL) vs. unequal length (UEL) headers. It's one of the most passionate arguments among WRX and STI owners, and for good reason — the choice affects not just power, but the iconic sound that makes Subarus so distinctive.

This guide breaks down everything you need to know to make the right header choice for your Subaru, whether you're building a street car, a track machine, or something in between.

Understanding the Subaru Boxer Engine Layout

Before diving into headers, it helps to understand why this debate exists in the first place. Subaru's horizontally-opposed (boxer) engine has cylinders on both sides of the crankshaft. In a traditional 4-cylinder layout, the firing order creates even exhaust pulses. In a boxer engine, the layout makes it geometrically challenging to create equal-length exhaust paths from all four cylinders to the turbocharger.

Subaru's solution on most models was to use an unequal length header — a design that's simpler and cheaper to manufacture, but creates uneven exhaust pulses. Those uneven pulses are what produce the famous Subaru "burble" or "potato potato" sound at idle.

Unequal Length (UEL) Headers

How They Work

In a UEL header, the exhaust runners from each cylinder bank are different lengths before they merge at the collector. This means exhaust pulses arrive at the turbocharger at uneven intervals, creating the characteristic Subaru sound.

Pros of UEL Headers

• The Subaru Sound: If you love the burble, UEL is the only way to keep it. Many enthusiasts consider this a non-negotiable part of the Subaru experience.
• Lower Cost: UEL headers are generally less expensive than EL headers due to simpler construction.
• Better Low-End Torque: The uneven pulse timing can actually benefit low-RPM torque in some applications, making the car feel punchier at street driving speeds.
• Easier Installation: UEL headers typically have simpler routing that's easier to work with in the engine bay.

Cons of UEL Headers

• Less Top-End Power: Uneven pulses are less efficient at scavenging exhaust gases, which limits top-end horsepower.
• Inconsistent Turbo Spool: Uneven pulse timing can cause the turbocharger to spool less efficiently, particularly at higher RPM.
• Power Ceiling: For high-power builds, UEL headers become a limiting factor.

Equal Length (EL) Headers

How They Work

Equal length headers route all four exhaust runners to the same length before they meet at the collector. This requires more complex bends and routing in the engine bay, but the result is perfectly timed exhaust pulses arriving at the turbocharger simultaneously.

Pros of EL Headers

• More Top-End Power: Balanced exhaust pulses allow the turbocharger to spool more efficiently and produce more power at higher RPM. Typical gains of 10–20 WHP over a comparable UEL header.
• Better Turbo Efficiency: Even pulse timing improves turbo spool characteristics, especially at mid-to-high RPM.
• Smoother Power Delivery: More linear power curve, which many drivers prefer for track use.
• Higher Power Ceiling: EL headers are the choice for serious high-power builds.

Cons of EL Headers

• No Subaru Burble: The signature sound disappears with EL headers. The exhaust note becomes more conventional — still good, but different.
• Higher Cost: More complex construction means higher price.
• More Complex Installation: The routing required for equal length runners can make installation more involved.
• Potential Fitment Challenges: Some EL headers require modifications to surrounding components for proper clearance.

Which Header is Right for Your Build?

Choose UEL If:

• You love the Subaru burble and it's important to your ownership experience
• You're building a street car focused on low-to-mid RPM performance
• You're on a tighter budget
• Your power goals are under 400 WHP
• You want an easier installation

Choose EL If:

• Maximum power is your priority
• You're building a track car or high-power street build
• You're targeting 400+ WHP
• You prefer a more linear, conventional power delivery
• You don't mind losing the signature Subaru sound

Header Materials: What to Look For

Stainless Steel

The most common material for aftermarket headers. Stainless steel offers excellent corrosion resistance, good heat tolerance, and long service life. Most quality aftermarket headers are made from 304 or 321 stainless steel. This is the right choice for the vast majority of street and track builds.

Inconel

A nickel-chromium superalloy used in motorsport and aerospace applications. Inconel headers are significantly lighter than stainless and handle extreme heat better. The tradeoff is cost — Inconel headers can be 3–5x the price of stainless. Best for dedicated race cars where weight and heat management are critical.

Mild Steel (Avoid)

Some budget headers use mild steel, which is prone to rust and has lower heat tolerance. Avoid mild steel headers for any serious performance application.

Fitment Guide by Model

• 2013–2021 WRX/STI (EJ257): Both UEL and EL headers are widely available. The EJ257 STI is the most popular platform for header upgrades.
• 2015–2021 WRX (FA20DIT): The FA20DIT already uses an equal length header from the factory. Aftermarket EL headers for this platform focus on improved flow over the stock unit rather than a layout change.
• 2015–2021 BRZ/FRS/86 (FA20): The naturally aspirated FA20 benefits from headers differently than turbocharged applications. Look for headers designed specifically for the NA FA20.
• 2022+ WRX (VB Chassis / FA24DIT): A newer platform with growing aftermarket support. Verify fitment carefully as the FA24 has different header requirements than the FA20.

Installation Tips

• Always use new header gaskets — never reuse old ones
• Apply anti-seize to all header bolts
• Allow the header to heat cycle 2–3 times before checking for leaks
• A tune is strongly recommended after any header installation on a turbocharged Subaru
• Check for heat shield clearance, especially on EL headers with complex routing

Shop Subaru Headers at XT Performance

We carry a curated selection of equal length and unequal length headers for the WRX, STI, BRZ, and more. All headers are verified for fitment on the specific Subaru platforms we support.

Browse our full Subaru Headers collection and find the right header for your build. Have questions about fitment or which header is right for your goals? Contact us — we're enthusiasts too and happy to help.