XFORCE Equal-Length 4-2-1 Stainless Steel Header & Up-Pipe – Subaru EJ20/EJ25 Turbo – TH-EJ20-TY
Equal-Length Performance Headers for Turbocharged Subaru EJ Engines
The XFORCE TH-EJ20-TY replaces the factory exhaust manifold and up-pipe on selected turbocharged Subaru EJ20 and EJ25 engines.
Its equal-length 4-2-1 Tri-Y configuration is designed to balance the exhaust pulses travelling from each cylinder, improving scavenging and creating a more consistent flow of exhaust gas towards the turbocharger.
Constructed from brushed 304-grade stainless steel and TIG welded throughout, the kit includes both the equal-length header and a matching high-flow up-pipe with an integrated stainless-steel flex section.
Important Sound Information
These are equal-length headers.
They will change the characteristic Subaru exhaust note.
Compared with the original unequal-length manifold, the exhaust note will generally become:
- Smoother
- More even
- Sharper at higher engine speeds
- Less dominated by the traditional Subaru burble
If retaining the strongest possible classic Subaru rumble is your priority, this is not the correct header. An unequal-length design would be the more appropriate choice.
The equal-length design is intended primarily for improved exhaust-pulse balance, scavenging and performance rather than preserving the original uneven boxer-engine sound.
Equal-Length 4-2-1 Tri-Y Design
The four equal-length primary pipes merge into two secondary sections before joining at the main collector.
This layout helps the exhaust pulses arrive at the collector at more evenly spaced intervals, supporting:
- Improved exhaust scavenging
- More balanced exhaust pulses
- Reduced exhaust restriction
- More consistent flow towards the turbocharger
- Improved throttle response
- Stronger performance potential
- Support for additional engine and turbocharger upgrades
Actual performance gains will depend on the vehicle, existing modifications and engine calibration. No specific power increase is guaranteed from fitting the header alone.
High-Flow Up-Pipe Included
The kit includes a matching stainless-steel up-pipe connecting the header collector to a compatible factory-position turbocharger.
Its 2.25-inch pipework provides a high-flow route into the turbine housing, while the integrated stainless-steel flex bellows allow for engine movement and thermal expansion.
This helps reduce stress on:
- Header welds
- Exhaust flanges
- Turbocharger mounting points
- Cylinder-head exhaust connections
The up-pipe is designed for compatible factory-position single-scroll turbocharger installations.
Brushed 304 Stainless-Steel Construction
Both the header and up-pipe are manufactured from 304-grade stainless steel and TIG welded throughout.
Benefits include:
- Resistance to corrosion
- Durability under high exhaust temperatures
- Strong welded joints
- Reduced exhaust restriction
- A clean brushed finish
- Suitability for road and performance applications
Tubular stainless-steel headers may radiate more heat into the engine bay than a factory manifold fitted with extensive heat shielding. Suitable heat management should be considered during installation.
Vehicle Compatibility
Designed for selected turbocharged Subaru vehicles using a compatible EJ20 or EJ25 engine, factory-position turbocharger and single-scroll exhaust configuration.
Subaru Forester
Selected turbocharged applications including:
- Forester SF GT
- Forester SG GT
- Forester SG XT
- Selected EJ20 turbo models
- Selected EJ255 turbo models
- Approximate catalogue coverage from 1997 to 2008
This kit is not intended for naturally aspirated Forester models simply because they use an EJ-series engine.
Subaru Impreza WRX and STI
Selected applications including:
- GC-generation WRX and STI
- GD and GG-generation WRX and STI
- GR and GV-generation WRX and STI
- Selected VA-generation STI models using the EJ257
- Approximate catalogue coverage from 1994 to 2021, depending on engine and turbocharger configuration
Fitment must be confirmed using the engine and turbocharger arrangement rather than relying on the registration year alone.
Important Single-Scroll Requirement
The TH-EJ20-TY is an equal-length header and up-pipe kit designed around a factory-position single-scroll turbocharger arrangement.
It is not suitable for:
- Factory twin-scroll turbocharger systems
- JDM Spec C models with twin-scroll exhaust arrangements
- Twin-scroll EJ207 applications without conversion
- FA20DIT-powered Subaru WRX models
- FA24-powered Subaru WRX models
- Naturally aspirated EJ engines
- Subaru BRZ or Toyota GT86 applications
- Rotated or non-standard turbocharger installations
The cylinder-head bolt pattern alone does not confirm compatibility. The turbo flange, up-pipe arrangement, sump clearance and exhaust configuration must also match.
If you are unsure, please contact us with your registration number, VIN, engine code and turbocharger configuration before ordering.
Engine Calibration
An ECU calibration is strongly recommended after fitting performance headers and an up-pipe, particularly where the vehicle also has:
- An upgraded downpipe
- A high-flow catalytic converter
- A larger turbocharger
- Modified boost control
- An upgraded intake
- Larger injectors
- Other exhaust modifications
A suitable calibration allows the vehicle’s fuelling, ignition timing and boost control to be checked against the altered exhaust flow.
Fitting performance parts without checking the engine calibration may prevent the vehicle from achieving the expected benefits and can create undesirable boost or fuelling behaviour.
Emissions and UK Road-Use Information
This product is not ECE approved.
It is supplied as a performance exhaust component. Road legality depends on the specification of the individual vehicle and whether any manufacturer-fitted emissions equipment is removed or altered during installation.
The supplied up-pipe is not described by XFORCE as containing a catalytic converter.
If the original vehicle has a catalytic converter or other emissions-control device within the manifold or up-pipe, fitting this component may remove manufacturer-fitted emissions equipment.
The purchaser and installer are responsible for confirming that the completed vehicle complies with:
- UK emissions requirements
- MOT requirements
- Road-noise limits
- Applicable construction and use regulations
This product is not guaranteed to be road legal for every listed application.
Any exhaust modification should also be declared to the vehicle’s insurer.
Sensor and Hardware Requirements
Sensor arrangements vary between Subaru models.
Before installation, confirm:
- Oxygen-sensor positions
- Exhaust-gas temperature sensor requirements
- Turbocharger inlet flange
- Cylinder-head flange arrangement
- Sump and oil-filter clearance
- Existing under-engine bracing
- Required gaskets, studs and nuts
New exhaust gaskets should be used during installation.
Additional gaskets, hardware or sensor adapters may be required depending on the vehicle and are not included unless specifically stated.
Technical Specifications
- Manufacturer: XFORCE
- Manufacturer part number: TH-EJ20-TY
- Product type: Header and up-pipe kit
- Engine family: Subaru EJ20 and EJ25 turbo
- Header type: Equal length
- Header configuration: Tri-Y
- Runner layout: 4-2-1
- Turbo configuration: Factory-position single scroll
- Primary pipe diameter: 1.75 inches
- Pipework after collector flange: 2.25 inches
- Material: 304-grade stainless steel
- Finish: Brushed stainless steel
- Welding: TIG welded
- Flexible section: Stainless-steel flex bellows
- ECE approved: No
- Approximate product weight: 9.25kg
- Package dimensions: 71 x 20 x 41cm
What’s Included
- 1 x XFORCE equal-length stainless-steel header assembly
- 1 x XFORCE high-flow stainless-steel up-pipe with flex bellows
Gaskets, studs, nuts, sensor adapters and heat-management products are not included unless specifically supplied with the kit.
Professional Installation Recommended
Replacing a Subaru turbo exhaust manifold and up-pipe is more involved than fitting a conventional cat-back exhaust.
Installation may require:
- Removal of the original manifold and heat shields
- Access to corroded exhaust studs and fasteners
- Turbocharger or up-pipe access
- New exhaust gaskets
- Inspection of oil-filter and sump clearance
- Checking for exhaust leaks
- Additional heat management
- ECU calibration
Professional installation by a Subaru or performance-exhaust specialist is strongly recommended.
Why Choose the XFORCE TH-EJ20-TY?
Because an equal-length header provides more evenly spaced exhaust pulses and improved scavenging compared with the original unequal-length layout.
Because reducing restriction before the turbocharger can improve response and support further performance upgrades.
And because the kit combines the equal-length header and matching high-flow up-pipe in one properly developed stainless-steel package.
Just remember: improved pulse balance comes at the expense of some of the traditional Subaru burble.
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