IAG Performance Unequal Length Header & Uppipe – Subaru Models (Inc. WRX 2002-2014 / STI 2004+)

IAG Unequal Length Header and Up-Pipe — 2002-2014 Subaru WRX / 2004-2021 STI

More Power and the Iconic Subaru Rumble
The IAG Unequal Length Header and Up-Pipe package replaces both the OEM exhaust manifold and up-pipe with stainless steel components engineered for improved power output, throttle response, and the characteristic Subaru boxer rumble that unequal length headers produce. Smooth mandrel bends, increased piping diameter, and durable stainless steel construction address the flow and weight limitations of the OEM components. Includes all required gaskets and zinc-plated hardware.

DETAILS

• Durable stainless steel construction on both header and up-pipe
• Unequal length header layout — produces characteristic Subaru boxer rumble
• Smooth mandrel bends throughout
• Increased piping diameter vs OEM
• Includes 3-bolt up-pipe
• Increases horsepower and torque
• Improves throttle response and reduces turbo lag
• Aggressive exhaust note
• Lighter than OEM cast exhaust manifold
• Includes zinc-plated hardware
• Includes new exhaust gaskets
• Fits: 2002-2014 WRX / 2004-2021 STI

Unequal Length Layout — Sound and Performance
The unequal length header design is what gives Subaru boxer engines their distinctive exhaust note at idle and low RPM. This is a desirable characteristic for Subaru enthusiasts, and it comes with measurable performance benefits: improved scavenging efficiency from the unequal length primary tubes enhances exhaust gas velocity and turbocharger spool characteristics.

Increased Flow Over OEM
The OEM Subaru exhaust manifold is a cast iron piece with significant flow restrictions and substantial mass. IAG’s stainless header uses smooth mandrel bends and increased piping diameter to reduce exhaust backpressure. Less backpressure means faster turbocharger spool, reduced pumping losses, and more net power.

Complete Package
The IAG header package includes both the header and the up-pipe in a single order. The up-pipe connects the header to the turbocharger inlet and is a critical part of the exhaust flow path. New gaskets and hardware are included for a complete installation.

Why Choose IAG Performance

IAG Performance has been building Subaru-specific engine and drivetrain components since 2001, and in that time they have become the standard by which serious Subaru builds are measured. Based in Westminster, Maryland, IAG designs, machines, and assembles their products in-house using Haas CNC equipment and their own engineering team. Their catalog spans everything from short blocks and long blocks rated to 1150 BHP all the way down to the fuel system, oiling, and drivetrain hardware that keeps modified Subarus running reliably for years. Every IAG product exists because a problem needed a better solution than what was available — and the engineering shows.

The RallySport Take

The IAG Unequal Length Header is the correct exhaust manifold upgrade for any WRX or STI build targeting improved low-RPM response and the iconic boxer exhaust character. Stainless construction, mandrel bends, and the up-pipe included — a complete, properly engineered package.

Fitment