Best Exhaust For Sti: Compare Cat-Back and Axle-Back Options

#1 · Best Overall

1. Borla 140595 Cat-Back

• Material: Stainless Steel
• Compatible with Vehicle Type: Car
• Weight: 48 lb

Best for: Drone-conscious cat-back buyers.

Why it ranks #1: Listed for 2015–2021 WRX and STI, it combines T-304 stainless steel, bolt-on installation, dual split rear exits, and a stated no-drone guarantee.

Borla’s no-drone guarantee is the key differentiator for buyers concerned about cabin drone, paired here with a cat-back system and dual split rear exits. The listing specifies T-304 stainless steel, bolt-on installation, and 2015–2021 WRX/WRX STI fitment.

The no-drone guarantee directly addresses a common concern when selecting a cat-back, while the dual split rear-exit layout establishes the system’s outlet arrangement. T-304 stainless steel and all-welded construction describe how the exhaust is made, and bolt-on installation provides a defined fitting method. The stated application covers 2015–2021 Impreza WRX and WRX STI with 2.0L or 2.5L four-cylinder engines, giving buyers a specific compatibility range to evaluate.

Skip it if you specifically want a single exit; the Tomei TB6090-SB02C is listed as a single-exit muffler kit.

This is for 2015–2021 WRX and WRX STI owners seeking a cat-back with dual split rear exits and a no-drone guarantee. Its dual-outlet layout is the main configuration boundary.

Listed on Amazon as: BORLA 140595 Cat-Back Perf. Exhaust Sys. for 2015-2021 Subaru Impreza WRX & WRX STI 2.0L/ 2.5L 4 Cyl. T-304 SS S-TypeDual Split Rear Exit Dual 3.5" Round Polished T-304 Stainless Tips Each Side

#2 · Best 3-Inch Piping

2. Invidia N1 Titanium Burnt Tip

• Material: Titanium
• Compatible with Vehicle Type: Car
• Weight: 47 lb

Best for: Burnt-tip dual cat-back fans.

Why it ranks #2: Fits 2015-up four-door WRX/STI and specifies 76 mm piping, 101 mm tips, mandrel-bent SUS304 stainless tubing, and burnt titanium tips.

Mandrel-bent stainless-steel piping and twin burnt-titanium outlets distinguish this Invidia N1 cat-back, with 3-inch pipes and 4-inch tips providing concrete sizing. The listing specifies 2015-and-newer four-door WRX/STI fitment and bolt-on installation, making body style and model range key selection points.

The 76 mm mandrel-bent piping is described as supporting exhaust flow and reducing back pressure, giving performance-minded buyers a stated purpose for its routing. CNC-machined flanges and bolt-on installation define the listed connection approach, while the polished SUS304 stainless construction provides the main system material. Twin single-layer burnt-titanium tips create the outlet look, and the 101 mm tip size is specified. Fitment is limited to 2015-up four-door WRX/STI models.

Skip it if you drive a two-door model; the Autozensation 263-WRX02 is listed for 2002–2007 WRX STI models.

This suits owners of 2015-up four-door WRX/STI models who want a dual-outlet cat-back with burnt titanium tips. Its four-door fitment boundary matters, as does its specific year range.

Listed on Amazon as: Invidia (HS15STIGTT) N1 Titanium Burnt Tip Dual Cat-Back Exhaust System for Subaru WRX/STI

#3 · Quad Titanium Tips

3. Invidia Gemini R400

• Material: Stainless Steel
• Compatible with Vehicle Type: Car
• Weight: 49.5 lb

Best for: Power-focused 2015-plus owners.

Why it ranks #3: The listing targets 2015+ WRX/STI and identifies a quad titanium-tip configuration, stainless construction, bolt-on installation, and included exhaust gaskets.

A 4-inch stainless-steel bell mount is the defining feature of this Invidia exhaust, which the listing connects with freeing excess gas and added power. Its stated 2015-and-newer WRX and STI application and bolt-on installation make it a candidate for owners seeking a performance-oriented exhaust change.

The listing describes the 4-inch stainless-steel bell mount as helping free excess gas, and cites a dyno chart showing several horsepower units added over the stock exhaust. That gives power-minded buyers a stated rationale beyond appearance. Bolt-on installation and included exhaust gaskets support a defined installation workflow, while the listing identifies 2015-and-newer Subaru WRX/STI compatibility. At 49.5 pounds, its listed weight is worth accounting for when planning handling and installation.

Skip it if you prioritize a lower listed system weight; the Extreme Online Store EXT-MD002 axle-back weighs 8 pounds.

This is for 2015-and-newer WRX/STI owners prioritizing the listed power rationale and bolt-on format. Account for its 49.5-pound listed weight, and ensure the vehicle falls within the stated application.

Listed on Amazon as: Invidia HS15STIGM4ST Exhaust System (Back Exhaust2015+ Subaru WRX/Sti Gemini/R400 Single Layer Quad Titanium Tip Cat)

#4 · Titanium Construction

4. Tomei Full Titanium Muffler

• Material: Titanium
• Compatible with Vehicle Type: Car

Best for: Titanium single-exit seekers.

Why it ranks #4: Its titanium muffler kit fits 2011–2021 STI EJ applications and includes hardware for bolt-on installation; verify the exact engine and body fitment.

Full titanium construction distinguishes this Tomei muffler kit, pairing a lightweight material choice with a single-exit configuration. Its stated vehicle applications span 2008–2014 WRX EJ, 2011–2021 STI EJ, and 2015–2021 WRX FA20DIT sedans, giving buyers several specified model ranges to check.

The titanium material sets this kit apart from the stainless-steel systems in this roundup, while its single-exit layout gives buyers a specific outlet configuration to choose. Tomei lists bolt-on installation and includes all hardware for that installation, helping owners plan around the supplied mounting components rather than sourcing them separately. Compatibility is specified for select WRX and STI engine and year ranges, so checking the exact listed application is central to choosing this kit.

Skip it if you want dual outlets; the Borla 140595 is listed with dual split rear exits.

This is for owners whose WRX or STI falls within Tomei’s stated engine and year applications and who want a titanium single-exit kit. Its single outlet is the key configuration boundary to weigh.

Listed on Amazon as: Tomei Full Titanium Muffler Kit Compatible with 2008-14 WRX EJ, 2011-21 STI EJ and 2015-21 WRX FA20DIT Sedan – Single Exit – TB6090-SB02C

#5

5. PHILTOP Cat-Back System

• Weight: 26.2 lb

Best for: 2015–2017 cat-back buyers.

Why it ranks #5: This cat-back is specifically listed for 2015–2017 WRX/WRX STI, with stainless-steel construction described, though detailed dimensions and installation information are absent.

A cat-back format specified for 2015–2017 Subaru WRX and WRX STI gives this PHILTOP system a clear fitment window and scope. The listing also identifies stainless-steel construction, larger pipes, low-restriction mufflers, and tuned resonators, tying the setup to its stated noise-reduction focus.

The larger pipes, low-restriction mufflers, and tuned resonators are listed as features that reduce noise, giving buyers a stated operating benefit rather than just a cat-back label. Stainless-steel construction is also specified, while the system’s 2015–2017 WRX/WRX STI fitment makes the model-year boundary important during selection. At 26.2 pounds, the listed weight is useful when planning handling and installation, though the supplied information does not specify included installation hardware.

Skip it if you own a 2018–2021 WRX or STI; the Borla 140595 is listed for 2015–2021 models.

This suits owners of 2015–2017 WRX or WRX STI models seeking a stainless cat-back with listed noise-reduction features. Its specified year range is the main fitment boundary to keep in view.

Listed on Amazon as: PHILTOP Cat-Back System Fit for 2015-2017 Subaru WRX/WRX STI

#6 · Burn-Finish Tips

6. Generic Burn Style Axle-Back

• Material: Stainless Steel
• Compatible with Vehicle Type: Car

Best for: Burn-finish axle-back shoppers.

Why it ranks #6: For 2015–2021 WRX/STI, this stainless axle-back specifies 2.50-inch piping and 4-inch double-walled tips with a polished burn finish.

The 4-inch double-wall tips combine a polished burn-steel finish with a defined visual upgrade, while the 2.50-inch piping keeps this setup focused on an axle-back change. It fits 2015–2021 Subaru WRX and WRX STI models, giving owners in that range a clearly specified application.

Stainless-steel construction and the polished burn finish make the muffler a visually distinctive replacement, while the double-wall 4-inch tips carry that finish to the visible outlets. Its 2.50-inch piping and axle-back format define the scope of the change rather than a full cat-back system. The stated 2015–2021 WRX and WRX STI fitment helps buyers narrow vehicle compatibility, and included mufflers and gaskets provide the listed components for installation.

Skip it if you need a complete cat-back system; the Borla 140595 is listed as a cat-back option.

This suits 2015–2021 WRX and WRX STI owners seeking a burn-finish axle-back with prominent double-wall tips. Its stated scope is the muffler section, so buyers seeking a complete cat-back should look elsewhere.

Listed on Amazon as: Generic Burn Style Stainless Axle Back Muffler Exhaust for Subaru WRX & STi 2015-2021, MF-SWRX15-BUR

#7

7. Generic Polished Axle-Back

• Material: Stainless Steel
• Compatible with Vehicle Type: Car

Best for: Polished axle-back replacement shoppers.

Why it ranks #7: It fits 2015–2021 WRX/STI and lists stainless construction, 2.50-inch piping, and 4-inch double-walled tips, but excludes aftermarket exhausts and SPT mid-pipes.

A polished stainless-steel finish and 4-inch double-wall tips give this Generic axle-back its defining appearance, while 2.50-inch piping specifies its outlet-side hardware. The listing covers 2015–2021 Subaru WRX and WRX STI models, but expressly excludes aftermarket exhaust systems and SPT midpipes.

The polished stainless-steel construction and double-wall 4-inch tips make the visible finish a central reason to consider this axle-back. Its 2.50-inch piping identifies the listed pipe size, while the axle-back scope keeps the replacement focused on the mufflers. Compatibility is specified for 2015–2021 WRX and WRX STI, with an explicit exclusion for aftermarket exhaust systems and SPT midpipes. Mufflers and gaskets are included, supporting planning around the stated components.

Skip it if you already have an aftermarket exhaust system or SPT midpipe; the Borla 140595 is a listed cat-back option.

This suits 2015–2021 WRX and WRX STI owners seeking a polished axle-back with double-wall tips. Its stated exclusion of aftermarket systems and SPT midpipes is a critical compatibility boundary.

Listed on Amazon as: Generic Polished Stainless Axle Back Muffler Exhaust for Subaru WRX & STi 2015-2021, MF-SWRX15-C

#8

8. Extreme Online Store Axle-Back

• Material: Stainless Steel
• Compatible with Vehicle Type: Fits ALL 2015-2021 Subaru WRX STi Models
• Weight: 8 lb

Best for: Complete axle-back hardware shoppers.

Why it ranks #8: This stainless axle-back fits all listed 2015–2021 WRX STI models and includes hangers, gaskets, and fasteners; its listing gives no piping diameter.

A paired left-and-right axle-back package includes hangers, gaskets, and nut-and-bolt pairs, making the Extreme Online Store option distinctive for buyers who want listed installation hardware together. It is specified for all 2015–2021 Subaru WRX STI models and uses polished stainless-steel double-wall quad tips.

The included left and right exhaust sections arrive with two pairs of hangers, a pair of gaskets, and nut-and-bolt pairs, so buyers can account for the listed hardware as they plan installation. Stainless-steel construction and polished double-wall quad tips provide a coordinated visible finish. The manufacturer states fitment for all 2015–2021 WRX STI models and says the product is test-fitted before shipment. Its axle-back format limits the change to that portion of the exhaust.

Skip it if you need a full cat-back replacement; the Invidia HS15STIGTT is listed as a cat-back system.

This fits WRX STI owners from 2015–2021 who value a paired axle-back package with its listed mounting hardware. It is not a complete cat-back, so consider the scope before choosing it.

Listed on Amazon as: Replacement For 2015-2021 Subaru WRX STi STAINLESS STEEL POLISHED SILVER Muffler Axle Back 4" Double Wall Quad Tips Exhaust

#9

9. Autozensation N1 Exhaust

• Compatible with Vehicle Type: Car

Best for: Older turbo WRX STI N1 seekers.

Why it ranks #9: A stainless N1-style exhaust for 2002–2007 turbo WRX/STI, it lists a removable silencer and included gaskets, hanger, and bolts, but not later generations.

A removable silencer distinguishes this Japanese N1-style Autozensation exhaust, letting owners choose whether to retain that listed component. Its specified fitment is limited to 2002–2007 Subaru Impreza WRX/STI 2.0L and 2.5L turbo models, with non-turbo versions excluded.

The removable silencer gives this N1-style exhaust a listed configuration option, while CNC-machined stainless steel and mandrel-bent construction describe its materials and pipe forming. The seller states that installation requires little modification and lists gaskets, a hanger, and bolts, giving buyers a clearer picture of the supplied fitting approach. Fitment is restricted to 2002–2007 WRX/STI 2.0L and 2.5L turbo models, so engine type and year are essential checks.

Skip it if you drive a non-turbocharged Impreza; the Spec-D Tuning MFCAT3-WRX02 also specifies turbo models only.

This suits turbocharged 2002–2007 WRX or STI owners seeking an N1-style exhaust with a removable silencer. The listed engine and year limits exclude non-turbo models and newer applications.

Listed on Amazon as: Autozensation Exhaust For 2002-2007 Subaru Impreza WRX STI

#10

10. Spec-D Tuning N1 Catback

• Compatible with Vehicle Type: Car
• Weight: 25 lb

Best for: Turbo WRX STI owners from 2002–2007.

Why it ranks #10: This stainless N1 cat-back is limited to 2002–2007 turbo WRX/STI models, making it unsuitable for later generations despite its specified cat-back layout.

A clearly defined 2002–2007 fitment window for turbocharged Subaru Impreza WRX and STI models is the central feature of this Spec-D Tuning N1 cat-back. The listing also says installation needs little to no modifications at best, helping buyers assess its stated fitting expectations.

The N1 cat-back is specified for 2.0L and 2.5L WRX/STI models from 2002–2007, but not non-turbocharged versions, making engine type a crucial compatibility check. Spec-D says installation is made easy and requires little to no modifications at best, which helps set expectations for the fitting process without promising a universal bolt-in result. The listed package is a cat-back exhaust system, and its 25-pound weight is useful for handling plans.

Skip it if you have a non-turbocharged Impreza; the Autozensation 263-WRX02 also excludes non-turbocharged models.

This fits owners of turbocharged 2002–2007 WRX or STI models seeking an N1 cat-back and a stated low-modification installation. Non-turbocharged models are expressly excluded from its application.

Listed on Amazon as: Spec-D Tuning Stainless N1 Catback Exhaust System