Flashark 2011-2021 Subaru WRX STI Sedan Cat-Back Exhaust System
Ready to Unleash the Boxer Roar? Give your WRX STI the aggressive sound it deserves with our Cat-Back Exhaust System, designed specifically for 2011–2021 WRX STI sedans. This system brings out the iconic rumble of the Subaru Boxer engine with a deep, free-flowing exhaust note that intensifies as you climb through the revs. At wide-open throttle, it delivers a raw, rally-inspired tone while maintaining a refined growl during normal driving with zero drone. Whether you're carving mountain roads or heading to work, this system transforms your daily drive into a performance experience.
Unleash the Signature Subaru Boxer Rumble with Performance and Style
✔ Dyno-Proven Gains: Instantly increase horsepower by 18HP and boost low-end torque for quicker acceleration and throttle response
✔ High-Flow Design: 3-inch mandrel-bent piping ensures smooth, unrestricted exhaust flow to maximize engine efficiency
✔ Deep, Aggressive Sound: Delivers a true rally-inspired tone under throttle, with a clean, low growl during daily cruising
✔ Durable TIG-Welded Construction: CNC-machined flanges and precision welds provide strength, pressure resistance, and long-lasting durability
✔ Direct Bolt-On Fitment: No modifications required—designed for a perfect fit on all 2011–2021 WRX STI sedans
✔ Available in Two Material Options: Choose between T-304 stainless steel for superior corrosion resistance, or 201 stainless steel for a more budget-friendly option without sacrificing performance
Please Note: When cleaning exhaust tips, especially the blue tip variants, which are made using a heat treatment process that can be removed with aggressive cleaning agents, make sure to use water and, only if necessary, a very gentle soap. Never scrub or use any rubbing or cleaning compound on these tips as the color will be damaged and will not be warranted.
Specifications:
| 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 / 210 Stainless Steel | 10 | Laser-cut for precise fit |
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 refers to the entire assembly that routes exhaust gases from the engine to the tailpipe. It includes components such as exhaust manifolds, catalytic converters, resonators, mufflers, and exhaust tips—playing a vital role in emissions control, noise reduction, and gas expulsion.
In contrast, a Cat-Back Exhaust system only covers the section from the back of the catalytic converter to the exhaust tip—excluding the catalytic converter itself. Upgrading to a Cat-Back system is a popular modification for those seeking improved exhaust flow, a deeper and more aggressive sound, and enhanced throttle response—all without altering the emissions-critical components near the engine. It’s a straightforward, emissions-compliant upgrade with noticeable gains and simple bolt-on installation.
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 |
Frequently Asked Questions: 2011-2021 Subaru WRX STI Sedan Cat-Back Exhaust System
Q1: Will this subaru wrx sedan cat-back exhaust system fit my specific year?
A1: Yes! This direct bolt-on kit is precision-engineered for a flawless fit on all 2011-2021 Subaru WRX STI sedan models. Whether you are upgrading your 2017 wrx sti exhaust, looking for a 2018 subaru wrx exhaust, or outfitting a 2021 sti exhaust, this system guarantees a perfect match to your factory hangers and catalytic converter.
Q2: Is this the subaru sti loudest exhaust system, and will it drone on the highway?
A2: While it delivers a raw, incredibly aggressive rally-inspired tone at wide-open throttle, it is not just obnoxiously loud. Enthusiasts rate this as the best exhaust for wrx sti because it unlocks that signature, deep Boxer engine rumble without the headache-inducing highway drone. You get a clean, low growl during daily cruising that turns into a roar when you hit boost.
Q3: How much power will this subaru sti performance exhaust add to my car?
A3: This subaru sti high-flow exhaust is dyno-proven to instantly increase your engine output by up to 18HP. By upgrading your restrictive stock piping to our wrx sti 3 exhaust upgrade, you significantly reduce backpressure. This maximizes exhaust gas flow, resulting in noticeably boosted low-end torque and much sharper throttle response.
Q4: What is the difference between the material options for this 2011-2021 subaru wrx sti sedan catback exhaust system, ss304 vs 201?
A4: We offer this wrx exhaust system in two variations to fit your budget and climate needs. The premium T-304 stainless steel (SS304) option provides superior, long-lasting corrosion and rust resistance, making it ideal for harsh weather or salted winter roads. The 201 stainless steel variant offers the exact same +18HP performance and deep Boxer sound, serving as a more budget-friendly option for milder climates.
Q5: Can I install this sti exhaust on wrx sedan models from the same generation?
A5: Absolutely. While specifically tuned to amplify the STI's rumble, this catback design shares structural mounting points with the standard WRX sedans from the same era. So, if you are searching for a 2016 wrx exhaust system, a 2017 subaru wrx exhaust, or a 2020 wrx catback exhaust, this system will bolt on perfectly to your vehicle.
Q6: Do I need to cut or weld anything to install this cat-back system for sti?
A6: Not at all! This subaru exhaust kit features a 100% direct bolt-on design. It utilizes heavy-duty 10mm laser-cut CNC-machined flanges that align perfectly with your OEM setup. The package includes the necessary gaskets, clamps, and hardware, meaning no custom fabrication or welding is required in your garage.
Q7: Will installing this subaru wrx aftermarket exhaust trigger a Check Engine Light (CEL)?
A7: No, it will not. Because this is a cat back exhaust subaru wrx system, it only replaces the piping from the back of the catalytic converter to the exhaust tip. It leaves your factory catalytic converter and O2 sensors completely untouched, ensuring you remain emissions-compliant while dramatically improving your car's sound and flow.
Q8: How do I clean and maintain the burnt blue tips on my new wrx sti exhaust system?
A8: To preserve the beautiful, heat-treated blue aesthetic on your exhaust tips, you must use only water and a very gentle car soap if absolutely necessary. Never use abrasive scrubbing pads, harsh chemical cleaners, or metal polishing compounds on the colored portion of the tips. Aggressive cleaning will strip the heat-treated color and void the finish warranty.
Q9: Why should I choose this over replacing my entire stock wrx exhaust?
A9: Upgrading your entire stock wrx exhaust (including headers and downpipes) alters emissions-critical components, which often requires expensive ECU tuning and can cause emissions test failures. Upgrading to this cat-back exhaust for subaru wrx gives you the massive sound improvement, the +18HP performance bump, and the premium rally aesthetic, all while remaining a simple, safe, and reliable bolt-on modification.
Q10: How durable is the construction of this subaru wrx cat-back exhaust system?
A10: Built by automotive enthusiasts for heavy track and street abuse, this subaru wrx performance exhaust utilizes professional TIG-welded construction. The strong 1.23–1.25mm thick bend pipes, combined with the heavy-duty 10mm CNC-machined flanges, provide unmatched structural strength and pressure resistance under heavy boost.
Q11: What makes the muffler inside this sti exhaust system sound so good?
A11: Inside the high-flow mufflers of our subaru wrx 2018 exhaust upgrade, we utilize a specialized 409 stainless steel perforated inner tube capped with heavy-duty 304 stainless steel. This carefully engineered internal core maximizes the scavenging effect while tuning out the annoying, high-pitched rasp, leaving nothing but the pure, aggressive Boxer roar.
Q12: Why is Flashark considered the best exhaust for sti owners looking for value?
A12: Flashark bridges the gap between premium motorsport engineering and accessible pricing. By offering high-end features like true 3-inch mandrel bends, dyno-proven +18HP gains, flawless TIG welding, and that iconic deep exhaust note, this subaru impreza wrx sti exhaust gives you top-tier rally performance without the massive markup found in other aftermarket brands.