Stratified 20G Ball Bearing Turbocharger 2004 - 2021 Subaru STI
The Modern OEM+ Turbo Upgrade for the EJ257
The Stratified 20G Ball Bearing Turbocharger is designed for STI owners who want substantially more power without sacrificing the response, drivability, and straightforward installation that make an OEM-location turbo so appealing.
Built around the proven 20G compressor and TD05H turbine combination, our modernized design adds a ball bearing CHRA, billet compressor wheel, and upgraded adjustable wastegate actuator to create a responsive turbo capable of supporting 450+ WHP with the proper supporting modifications.
The result is an excellent match for a street, track, or stock-engine STI: OEM-like spool around 3500 RPM with over 100 WHP of additional top-end potential compared to the factory turbo.
Responsive Power Without Going Rotated
Making more power from an EJ257 doesn't have to mean sacrificing response or converting the car to a complicated rotated turbo setup.
The 20G's 52.5/68 mm billet compressor wheel provides substantially more airflow than the factory turbo while the 49.2/55.8 mm TD05H turbine and 8 cm² turbine housing keep response sharp. Combined with the ball bearing CHRA, this gives the turbo the fast transient response and broad powerband that make an STI enjoyable on the street and coming out of corners on track.
Instead of chasing a large peak horsepower number at the expense of the rest of the powerband, this turbo is designed to deliver strong midrange torque with considerably more airflow and power toward redline.
True OEM-Location Drop-In Installation
The turbo retains the factory-style inlet, mounting location, and orientation, allowing it to install without the extensive modifications associated with rotated turbo systems.
All required turbo gaskets and oil feed lines are included, making this a complete, straightforward upgrade for an EJ-powered STI.
Upgraded Wastegate Control
Each turbo includes a billet adjustable wastegate actuator with a reinforced mounting bracket for stable and consistent boost control.
Three actuator springs are supplied with the turbo, with a 1 bar spring configuration pre-installed. This allows wastegate base pressure to be configured to suit different boost levels and engine combinations.
An Ideal Stock-Engine STI Turbo
For customers looking to maximize the performance of a stock-long-block EJ257 while retaining excellent response and drivability, the Stratified 20G hits the sweet spot.
Paired with typical supporting modifications such as a high-flow exhaust, intake, intercooler, 1050cc injectors, upgraded in-tank fuel pump, flex fuel where supported, and a quality calibration, the 20G delivers the airflow needed to transform the STI without requiring a complete change in turbo system architecture.
Finally, because every combination is different, Stratified custom tuning is available to properly calibrate boost, fueling, ignition timing, and supporting engine controls for your specific setup.
Power Numbers:
Turbo Kit Includes:
- Stratified Turbocharger
- Full Install Kit
- Turbo Outlet to Downpipe Gasket
- Turbo Oil Line and Copper Washers
- Exhaust Manifold Studs and Nuts
- Wastegate with 1 bar spring pre-installed and differnt springs to adjust
Stratified Turbo Features:
- 450+ WHP capable with appropriate fuel and supporting modifications
- OEM-like spool around 3500 RPM
- 20G billet compressor wheel – 52.5/68 mm
- TD05H turbine – 49.2/55.8 mm
- 8 cm² turbine housing
- Ball bearing CHRA
- Billet adjustable wastegate actuator
- Reinforced wastegate actuator bracket
- Three wastegate springs included
- 1 bar wastegate spring configuration pre-installed
- OEM-location, direct-fit configuration
- OEM-style compressor inlet and turbo orientation
- Turbo gaskets and oil feed lines included
- Excellent choice for responsive street and track builds
The 20G has long been one of the best turbo sizes for a responsive EJ-powered STI. We've taken that proven compressor and turbine combination and updated it with modern components, machining, ball bearing technology, and improved wastegate control.
For the STI owner who wants 450+ WHP capability without turning the car into a laggy big-turbo build, this is the turbo we recommend.
The Best Tuning Experience for your new Stratified Turbo
At Stratified we pride ourselves in offering our customers the most complete tuning experience. We hold paramount in providing the most robust tunes on the market while adding a touch of unique personality to each client’s calibration. We would love to pair your turbo purchase with our tuning support!
With an engineering background, years of experience tuning turbocharged vehicles and the help of the Cobb Accesspor / EcuTek ECUConnect we are able to offer a comprehensive tuning service for your STI that complements your new turbo beautifully for both power and driveability.
ProTune Sold Separately **$125 Non-Stock Turbo Tuning Fee Waived when purchasing turbo**
Subaru WRX STI Pro Tune
If you already have a tune with us, you can get a Top-Up Tune instead.
Any further questions - please feel free to Contact Us. Please remember to check your email for the online Tuning Form after you have purchased the tune. This document tells you how to take required datalogs and the tuning form inside the document must be completed prior to starting the tune itself.
**If order needs to be shipped outside of the USA or Canada, additional shipping charges will be calculated and added after the purchase.
