2011-2021 Subaru WRX STI 2.5L Turbo Sedan 4-Door Cat-Back Exhaust System
This direct bolt-on cat-back exhaust is made for the 2011-2021 Subaru WRX STI 4-door sedan — the GV-chassis model with the factory 2.5L EJ257 turbocharged Boxer-4. It replaces the piping from the rear of the catalytic converter to the tailpipe and is available in T-304 or 201 stainless steel, so you can match the material to your climate and budget. Verify your exact model in the fitment section below before ordering: this kit is sedan-specific and does not fit the hatchback or the non-STI WRX.
Built on a 3-inch mandrel-bent layout with TIG-welded joints and 10 mm CNC-machined flanges, the system ships with two main pipes, a silencer tail pipe, and the gaskets, clamps, and hardware needed to join them. Both material options share the same pipe layout and included parts, so the only decision between the two variants is the stainless grade.
Specifications
Applies to both material variants (T-304 and 201 stainless steel).
| Component | Material | Thickness (mm) | Notes |
|---|---|---|---|
| Bend Pipes | 304 / 201 Stainless Steel | 1.23 – 1.25 | Two material options available |
| Inner Perforated Tube (Muffler) | 409 Stainless Steel | 0.95 – 0.97 | Located inside the muffler body |
| Perforated Tube End Cap | 304 Stainless Steel | 0.87 | Cap the inner mesh tube |
| Flanges | 304 / 201 Stainless Steel | 10 | Laser-cut for precise fit |
Key Features
- Converter-Back System Scope: This kit replaces the exhaust section from the rear of the catalytic converter to the tailpipe, leaving the factory catalytic converter and O2 sensors in their original positions — a mid-to-rear upgrade rather than a full exhaust replacement.
- 3-Inch Mandrel-Bent Main Piping: The main pipes run at 3 inches in diameter with mandrel bends and 1.23–1.25 mm stainless walls, so the system keeps one uniform pipe path — the figure to match if you plan to pair it with other 3-inch exhaust sections.
- Two Stainless Grades, Same Layout: The identical pipe layout and included hardware are offered in T-304 or 201 stainless. T-304 gives higher corrosion resistance for wet or salt-treated regions; 201 is the budget-minded grade for milder climates — pick by environment first, then budget.
- TIG-Welded Joints with 10 mm CNC Flanges: Joints are TIG-welded and the flanges are 10 mm laser-cut, CNC-machined pieces that the gaskets, clamps, and factory mounting points bolt to.
- Perforated-Core Muffler Structure: Inside the muffler body, exhaust passes through a 409 stainless perforated inner tube capped with a 304 stainless end cap — the internal silencing structure of the system as listed in the specifications table.
- Hardware Kit Included: Gaskets, clamps, and mounting hardware ship with the pipes, so the included sections can be joined with standard hand tools and no extra parts for the kit itself.
Care tip — if your kit ships with the heat-treated blue tips, the colored surface is a finish layer and not a coating. Clean only with water (and a small amount of mild soap if needed) and never use abrasive pads or rubbing compounds, otherwise the blue color will be removed and that type of surface wear is not covered.
What's In The Box?
- 1 × Silencer Tail Pipe
- 2 × Main Pipe A
- 1 × Gaskets, Clamps, and Hardware Kit
Exhaust System vs. Cat-Back Exhaust
The exhaust system is the full assembly that routes gases from the engine to the tailpipe — exhaust manifolds, catalytic converters, resonators, mufflers, and exhaust tips — and it handles emissions control, noise reduction, and gas expulsion together.
A cat-back exhaust covers only the section from the rear of the catalytic converter to the tailpipe, excluding the converter itself. If you want to change the mid and rear piping while keeping the catalytic section as it is, a cat-back is the part of the system that matches that scope. If you intend to also change the downpipe, headers, or converter, a full exhaust replacement is the broader option — confirm which parts you plan to modify before ordering.
Check Before Ordering
- Confirm your vehicle: 2011-2021 Subaru WRX STI 4-door sedan, GV chassis, factory 2.5L EJ257 turbocharged Boxer-4 — check the model year and body style on your registration or VIN plate.
- Does not fit: WRX hatchback (5-door), 2008-2010 WRX STI (pre-GV), standard 2.0L WRX, and any non-sedan configuration. This kit is not interchangeable across those body styles.
- Modified or damaged exhaust: If the existing piping, hangers, or flanges were replaced, repaired after an accident, or altered from factory, confirm the mounting condition with our support team before you order.
- Blue tip care: The heat-treated blue tips must be cleaned with water only and, if absolutely necessary, a very gentle soap. Never scrub or use rubbing compounds or chemical cleaners — aggressive cleaning removes the heat-treated color and voids the finish warranty.
Shipping & Returns
Free U.S. Shipping: Orders are typically processed within 1–2 business days and delivered within 7–9 business days. Additional charges may apply to remote areas.
30-Day Returns: Unopened and unused items in their original packaging may be returned within 30 days of receipt. Return shipping is covered for verified quality issues.
Worry-Free Delivery: Optional protection against eligible loss, theft, delay, or transit damage is available at checkout.
Looking for more exhaust options? Browse our complete Exhaust System collection, the dedicated Cat-Back Exhaust category, or the Subaru Cat-Back Exhaust lineup. For complete upgrade packages, see our Exhaust System Kits. Limited-time offer: save on the entire Subaru exhaust lineup during our Labor Day Sale.
Fitment & Compatibility
| Brand | Model | Year Range | Full Compatible Specs |
|---|---|---|---|
| Subaru | WRX STI Sedan | 2011-2021 | 4-Door Sedan Body Style; GV Chassis; 2.5L EJ257 Turbocharged Boxer Flat-4 (H4) Factory Engine |
2011-2021 Subaru WRX STI Sedan Cat-Back Exhaust FAQs
Q1: Does this cat-back exhaust fit every 2011-2021 Subaru WRX STI sedan?
A1: Yes, when the vehicle is the 2011-2021 Subaru WRX STI 4-door sedan on the GV platform with the factory 2.5L EJ257 turbocharged Boxer-4. All model years in that range share the same sedan body and mounting layout, so this one kit covers 2011 through 2021 STI sedans. Hatchback and pre-2011 STI models are not covered.
Q2: Will this fit a standard WRX sedan or a WRX hatchback?
A2: No. This system is built for the WRX STI 4-door sedan only. It is not designed for the standard 2.0L WRX, the WRX hatchback (5-door), or the 2008-2010 STI models. For those vehicles, check the WRX listings in our Subaru cat-back collection instead.
Q3: Which section of the exhaust does this system replace?
A3: It replaces the piping from the rear of the catalytic converter to the tailpipe — the mid and rear sections. The factory catalytic converter and O2 sensors stay in their original locations because the kit starts behind the converter.
Q4: What is included in the box?
A4: The kit ships with one silencer tail pipe, two main pipes (A), and a gasket, clamp, and hardware kit. Mounting hardware for the included sections is supplied; you provide standard hand tools for the installation.
Q5: What is the difference between the T-304 and 201 stainless options?
A5: The pipe layout, diameter, and included parts are the same; the difference is the grade of stainless steel. T-304 offers higher corrosion resistance and suits wet climates or roads treated with winter salt. The 201 option is the budget-friendly grade for milder environments.
Q6: Do I need to cut or weld anything to install it?
A6: No. The system is designed as a direct bolt-on using the factory hanger locations and flange points, and the gaskets and clamps needed to join the sections are included. As with any exhaust install, confirm that your existing piping is unmodified and in good condition before you start.
Q7: Will this system affect the catalytic converter or trigger a check-engine light?
A7: It does not relocate or modify the catalytic converter or the O2 sensors, because the kit only covers the piping behind the converter. Whether any given vehicle logs a code depends on the vehicle's overall condition and setup, so no check-engine-light outcome can be guaranteed — if you are tuning or changing other exhaust parts, confirm with your tuner.
Q8: How do I clean the burnt blue exhaust tips?
A8: Use only water and, if needed, a very mild car soap on the heat-treated blue tips. Never scrub them or use rubbing compounds, metal polishes, or aggressive chemical cleaners — those will strip the heat-treated color and void the finish warranty.
Q9: How is this different from replacing my entire exhaust?
A9: A full exhaust replacement also changes components ahead of the catalytic converter, such as the downpipe or headers. This cat-back kit stops behind the converter, so the emissions-related front section is left untouched and the modification is limited to the mid and rear piping. Choose the option that matches how much of the system you plan to change.
Q10: How is the system constructed?
A10: The main pipes are 3-inch mandrel-bent stainless with 1.23–1.25 mm walls, the joints are TIG-welded, and the flanges are 10 mm laser-cut, CNC-machined pieces. The T-304 or 201 grade applies to the bend pipes and flanges, while the muffler's inner tube is 409 stainless with a 304 end cap.
Q11: What is inside the muffler?
A11: Inside the muffler body, the exhaust passes through a 409 stainless perforated inner tube with 0.95–0.97 mm walls, capped by a 0.87 mm 304 stainless end cap. That perforated-tube core is the internal silencing structure of the system, as listed in the specifications table.
Q12: How do I confirm my car is the GV / EJ257 version?
A12: Check the model year on your registration or VIN plate and confirm it is a 2011-2021 WRX STI 4-door sedan. The GV chassis with the 2.5L EJ257 engine is the US-market WRX STI sedan configuration for those years. If the badge, body style, or year range is unclear, message us with your VIN before ordering.