GrimmSpeed Equal Length Header – 2022-2025 Subaru WRX

Equal Length Header for the VB WRX: The Exhaust Manifold the FA24 Deserves

The GrimmSpeed Equal Length Header for the 2022-2025 Subaru WRX replaces the factory unequal length exhaust manifold with a true equal length design — consistent primary runner lengths from all four cylinders to the turbocharger inlet. The equal length design improves exhaust scavenging efficiency, eliminates inter-cylinder pulse interference at the turbine inlet, and replaces the factory boxer rumble with a sharper, more aggressive 4-cylinder exhaust character. For FA24WGT builds targeting maximum performance, the exhaust manifold is the component to address.

Equal Length Primaries — Consistent Pulse Timing at the FA24 Turbine

The factory FA24WGT exhaust manifold is unequal length — the four cylinder primaries vary in length, producing the characteristic Subaru boxer exhaust note but creating inconsistent exhaust pulse timing at the turbocharger turbine inlet. At moderate power levels this is manageable, but as boost and exhaust flow increase, unequal pulse timing creates interference between exhaust events and limits scavenging efficiency. The GrimmSpeed equal length header ensures all four cylinder pulses arrive at the turbine simultaneously — improving turbine efficiency, reducing turbo lag, and enabling higher power levels that the factory manifold would otherwise restrict.

304 Stainless Construction, Direct Bolt-In, O2 Sensor Bungs Retained

The GrimmSpeed header is constructed from 304 stainless steel with smooth mandrel bends throughout — the surface finish and bend geometry minimize turbulence in the exhaust flow path for maximum efficiency. Factory O2 sensor bung positions are retained for ECU compatibility. The header bolts directly to the FA24WGT’s factory turbocharger inlet and cylinder head mounting points — professional installation is recommended given the complexity of the exhaust manifold replacement on this platform. A tune is required after installation.

Key Features

• Platform: 2022-2025 Subaru WRX FA24WGT
• 304 stainless steel — mandrel-bent smooth flow path
• Equal length primary runners — consistent exhaust pulse timing to turbine
• Improves exhaust scavenging efficiency and reduces turbo lag
• Factory O2 sensor bung positions retained
• Direct bolt-in at factory exhaust manifold mounting points
• Replaces factory boxer exhaust note with 4-cylinder exhaust character
• Tune required after installation
• Professional installation recommended

Fitment Notes

• Platform: 2022-2025 Subaru WRX FA24WGT
• Tune required after installation
• Professional installation recommended
• Changes exhaust note from factory boxer rumble to 4-cylinder character

Straight From Subispeed

The GrimmSpeed equal length header is for VB WRX builds that have addressed intake, intercooler, and downpipe and are now looking at the exhaust manifold as the next restriction. It’s not an early build purchase — it’s for owners who are building seriously and want the exhaust manifold to match the rest of the system’s capability. The trade-off of losing the Subaru boxer exhaust note is real and worth considering; for a performance-focused build it’s a trade-off most owners make willingly.

What’s Included

• GrimmSpeed Equal Length Header
• New exhaust manifold hardware

About GrimmSpeed

GrimmSpeed is a Pacific Northwest-based performance parts manufacturer that has been building Subaru-specific hardware since 2003. Founded by engineers who were actively building and racing Subarus themselves, GrimmSpeed’s catalog reflects the priorities of people who use the products they make — turbo inlets, downpipes, uppipes, boost controllers, intercoolers, and engine bay accessories designed specifically for the EJ and FA-series Subaru platforms. Every GrimmSpeed product is engineered, tested, and refined in-house, and their focus on Subaru means the fitment and function reflect a deep understanding of the specific platforms they cover. Subispeed carries the full GrimmSpeed catalog because their approach to product development consistently produces parts that perform as advertised and fit correctly out of the box.

Year	Make	Model	Notes
2022-2025	Subaru	WRX	FA24WGT — all trims