Upgrading the exhaust on a Subaru WRX can improve both performance and tone, whether you’re chasing a sportier soundtrack or a lightweight, free-flowing system. This guide highlights five reputable exhaust options tailored to WRX and WRX STI models from 2015 through 2021, including axle-back and cat-back configurations. Each option emphasizes durability, stainless steel construction, and compatible fitment to help you decide the best route for your build. Below is a quick summary of the selected products to compare at a glance.
| Product | Brand | Type | Key Feature |
|---|---|---|---|
| Replacement For 2015-2021 Subaru WRX STi Stainless Steel Polished Silver Muffler Axle Back 4″ Double Wall Quad Tips Exhaust | Extreme Online Store | Axle Back Exhaust | Stainless Steel, double wall quad burnt tips |
| Generic Burn Style Stainless Axle Back Muffler Exhaust for Subaru WRX & STi 2015-2021, MF-SWRX15-BUR | Generic | Axle Back | Burn steel finish, 4″ OD tips |
| Replacement For 2015-2021 Subaru WRX STi Stainless Steel Polished Silver Muffler Axle Back 4″ Double Wall Quad Tips Exhaust | Extreme Online Store | Axle Back Exhaust | Complete axle-back set, included gaskets and hardware |
| Spec-D Tuning 4″ Stainless Catback Exhaust Dual Tip System Compatible with 2008-2014 Subaru Impreza WRX Sti Sedan | SPEC-D TUNING | Catback | Direct-fit for older WRX/STi models with easy installation |
| REV9 CB-083 FlowMaxx Stainless Steel Cat-back Exhaust Quad-tip system for Subaru WRX (VB) 2022-2025 All Trims | Rev9 | Catback | Double-walled quad-tip design, improved flow and comfort |
Replacement For 2015-2021 Subaru WRX STi Axle Back Exhaust
The Extreme Online Store axle-back exhaust is designed for 2015-2021 Subaru WRX and WRX STI models. It features a stainless steel construction with double-wall quad burnt tips that deliver a distinctive look and tone. The kit includes a left and right exhaust, hangers, gaskets, and the necessary hardware for installation. It is marketed as brand-new and unused, with a packaging-ready presentation. This option is ideal for owners who want a visible performance upgrade without a mid-pipe modification.
Generic Burn Style Stainless Axle Back Muffler Exhaust for WRX & STi
This Generic burnout-style axle-back exhaust emphasizes a polished burn steel finish with a 4.0″ OD double-walled tip and 2.50″ OD piping. It suitsWRX and STi models from 2015-2021, providing a more aggressive appearance and potential sound benefits. The product focuses on straightforward bolt-on installation and a robust stainless steel build, making it a practical option for enthusiasts seeking a mid-range upgrade without extensive modifications.
Replacement For 2015-2021 Subaru WRX STi Axle Back Exhaust (Quad Tips)
This second Extreme Online Store option targets all 2015-2021 WRX/STi models with a complete axle-back kit including left and right exhausts, two hangers per side, gaskets, and required nuts and bolts. The package is intended for a full rear-end upgrade, keeping the same general configuration as the first option but providing an alternative styling choice with the same fitment scope. It is marketed as brand-new and ready for installation.
Spec-D Tuning 4″ Stainless Catback Exhaust System for 2008-2014 WRX STI
The SPEC-D Tuning cat-back system is designed for 2008-2014 Subaru Impreza WRX/STi sedans, offering a 4″ stainless design with dual tips. It emphasizes straightforward installation with clear fitment notes and a direct-match approach to the factory layout. This option is targeted toward owners with older WRX/STi models looking to improve exhaust flow and tone with minimal modification requirements.
REV9 FlowMaxx Cat-back Exhaust for Subaru WRX VB (2022-2025)
The REV9 FlowMaxx cat-back system is designed for 2022-2025 Subaru WRX models, including VB chassis across all trims. Featuring a 2.5″ inlet and 3.5″ polished stainless steel double-walled tip, it focuses on improved exhaust flow and reduced cabin noise for a more comfortable ride. The kit aims for a direct-fit installation with an emphasis on performance gains and a refined, sporty sound characteristic of newer WRX iterations.
BORLA 140595 Cat-Back Exhaust for 2015-2021 WRX & WRX STI
Borla’s cat-back system for 2015-2021 Subaru Impreza WRX and WRX STI uses T-304 stainless construction with all-welded, bolt-on installation. The dual split rear exit tips provide a high-end aesthetic and a reputable performance-focused design. This option is ideal for drivers seeking a premium brand with a proven track record in tone control and durability across modern WRX platforms.
Replacement For 2015-2021 Subaru WRX STi Mid-Pipe Kit
The 3″ mid-pipe kit from Extreme Online Store targets WRX STi models within 2015-2021 to accompany exhaust upgrades. It includes 1 X Subaru WRX STi 3″ mid-pipe tube and multiple gaskets, aiming to deliver a balanced mid-section upgrade that complements axle-back or cat-back assemblies. The kit emphasizes a comprehensive sealing solution for a reliable fitment with reduced exhaust leaks.
Buying Guide: Key Considerations for Subaru WRX Exhaust Upgrades
- Fitment and model range: Confirm the system is compatible with your WRX generation and any specific trim (WRX, WRX STI, or Impreza variants) to avoid clearance or mounting issues.
- Cat-back vs axle-back: Cat-back systems replace the entire rear section and typically improve flow more than axle-back kits, while axle-back focuses on the rear muffler section for easier, lower-cost upgrades.
- Materials and finish: Stainless steel builds (T-304 or 409) resist corrosion. Double-wall tips and burn or polished finishes offer both aesthetics and durability.
- Installation: Look for bolt-on designs with included hardware and gaskets. Some systems require minor modifications or professional installation.
- Sound and flow: Higher-flow designs generally yield louder exhaust notes and improved flow, affecting cabin resonance and overall driving feel. Consider your noise tolerance and local regulations.
- Brand reputation and warranty: Reputable brands (Borla, REV9, SPEC-D, Borla) often provide longer warranties and consistent performance data. Evaluate customer reviews and warranty terms before purchase.
- Compatibility with other components: If you already have a different mid-pipe or turbo-back setup, ensure the chosen exhaust complements that configuration and does not conflict with the rest of your system.
- Maintenance and heat tolerance: Stainless steel systems are corrosion-resistant, but heat management remains important. Consider heat-shielded routes and compatible clamps to minimize heat damage to nearby components.
- Tuning considerations: Some exhaust upgrades may require minimal ECU adjustments or do not require tuning. Verify with a professional if you plan to pursue additional performance modifications.
- Legal and noise restrictions: Ensure the chosen exhaust complies with local noise ordinances and emissions regulations for street use.