Stainless Steel Header For Subaru Impreza (1997-2005) with 2.5L Engine

Purpose-built for the naturally aspirated EJ25, this stainless steel header delivers measurable power gains and improved throttle response for your 1997-2005 Impreza 2.5L (including 1998-2005 Impreza RS).

Get More From Your EJ25: Built for the Non-Turbo Boxer

The Impreza RS carved out its own identity in Subaru's lineup with the naturally aspirated EJ25 2.5L boxer engine. While it didn't have the turbocharged punch of the WRX, the RS offered AWD capability, balanced handling, and a smooth-revving powerplant that appealed to drivers who valued all-weather traction without the boost. For enthusiasts looking to extract more from the EJ25, the restrictive factory exhaust manifold was always the first bottleneck to address.

This 4-2-1 Tri-Y header replaces that factory restriction with a high-flow design engineered specifically for the non-turbo boxer engine. By optimizing exhaust scavenging and reducing backpressure, you'll gain 10-15 horsepower and torque across the rev range. Throttle response sharpens, mid-range pull improves, and you'll notice a more purposeful exhaust note that complements the iconic boxer rumble.

Key Features at a Glance

• T-304 Stainless Steel Construction: Resists rust and corrosion even in wet climates and winter road salt conditions.
• 4-2-1 Tri-Y Design: Merges exhaust pulses in stages to maximize scavenging efficiency and maintain low-end torque.
• TIG Welded CNC Machined Flange: Precision-built for leak-free fitment and long-term durability.
• 1.50" Primaries / 2.25" Collector: Sized specifically for the naturally aspirated EJ25's flow characteristics.
• Metal Gasket Included: High-quality gasket ensures a proper seal from day one.

Installation & Fitment

This header is a direct bolt-on replacement for your factory exhaust manifold. Due to the tight engine bay layout typical of Subarus, professional installation is strongly recommended to ensure proper clearances and torque specifications. All necessary gaskets and hardware are included in the kit, so your installer will have everything needed for a complete swap.

Durability & Material Details

T-304 stainless steel is the gold standard for exhaust components, offering exceptional resistance to heat cycling and environmental corrosion. Whether you're driving through salty New England winters or humid coastal climates, this header maintains its structural integrity and appearance far longer than mild steel alternatives. The precision TIG welds and CNC-machined flange ensure consistent sealing and long-term reliability.

Your Benefits at a Glance

• Improved Power Delivery: Gain noticeable acceleration and passing power across the rev range.
• Enhanced Boxer Sound: A deeper, more aggressive tone that highlights the EJ25's character.
• Perfect Foundation Mod: Pairs seamlessly with a cat-back exhaust or cold air intake for compounded gains.

Specifications

Fitment:

• 1997-2005 Subaru Impreza 2.5L (1998-2005 US-spec Impreza RS)
• 2.5L Non-Turbo EJ25 engines only

Package Includes:

• 1 x Stainless Steel 4-2-1 Tri-Y Header Exhaust System
• Metal Gasket(s)
• All necessary mounting hardware and bolts

Common Questions

Will this header fit my 1998-2005 Subaru Impreza RS 2.5L?
Yes. This 4-2-1 Tri-Y stainless steel header is a direct bolt-on replacement engineered specifically for the naturally aspirated 2.5L EJ25 boxer engine in the Subaru Impreza.

Will this fit a turbocharged Impreza WRX or STI?
This header is built exclusively for naturally aspirated (non-turbo) 2.5L EJ25 engines.

What is included in the box?
The kit includes the T-304 stainless steel 4-2-1 Tri-Y header, metal gasket(s), and all necessary mounting bolts and hardware for installation.

What are the primary and collector tube diameters?
It features 1.50-inch primary tubes that merge into a 2.25-inch collector, sized to optimize exhaust scavenging on the non-turbo 2.5L engine.

Does installation require welding or cutting?
It is a direct bolt-on replacement for the factory exhaust manifold using the supplied hardware and gaskets. Professional installation is recommended due to tight engine bay clearances.