The Subaru BRZ / Toyota GR86 platform has become a modern icon for driving purists, celebrated for its low center of gravity, balanced chassis, and naturally aspirated boxer engine. Yet the stock exhaust system, while compliant, often leaves enthusiasts wanting more—both in terms of sound character and performance. The APEXi exhaust system is a choice upgrade that addresses these desires directly. This article takes a detailed look at how an APEXi exhaust system can unlock your GR86’s potential, from measurable horsepower gains to a richer, more aggressive exhaust note that transforms every drive.

The Engineering Behind the APEXi Exhaust System

Premium Materials and Construction

APEXi has a long-standing reputation in the Japanese aftermarket industry for manufacturing high-quality performance parts. Their GR86 exhaust systems are typically constructed from T-304 stainless steel, a corrosion-resistant and durable alloy that can withstand high temperatures and road grime. This material choice ensures a long service life, often outlasting the vehicle itself. The use of stainless steel also provides a clean, polished appearance that contrasts well with the underside of the car.

Some APEXi models, such as the popular EXH EVO-R lineup, feature a combination of stainless steel piping with a titanium muffler tip. This hybrid approach reduces weight at the extreme rear of the vehicle, contributing to a slight improvement in weight distribution and overall mass reduction. The titanium tip also develops a unique bluish tint over time, adding a subtle visual cue of the system’s performance pedigree.

Mandrel-Bent Tubing for Unrestricted Flow

A critical feature of any high-performance exhaust is the method used to shape the piping. APEXi utilizes mandrel bending to ensure that every bend in the exhaust path maintains a consistent inner diameter. Unlike crush bending, which can create restrictions and turbulence, mandrel bending allows exhaust gases to flow freely from the headers to the tailpipe. This smooth flow path reduces back pressure, which is a key factor in unlocking additional horsepower and torque from the FA24 engine.

Resonator and Muffler Design

The sound profile of an exhaust system is largely dictated by the internal design of its resonators and mufflers. APEXi engineers carefully tune these chambers to eliminate unwanted drone while preserving a sporty, aggressive note. Many APEXi systems incorporate a straight-through perforated core inside the muffler, which absorbs high-frequency noise without creating excessive back pressure. The result is a clean, deep exhaust tone that builds steadily with RPM and does not become obnoxious during highway cruising.

Some variant models also offer adjustable exhaust valves or interchangeable silencers. For example, the APEXi N1 EXE system (designed for earlier Subaru platforms, but conceptually similar) allowed drivers to swap between a street-friendly silencer and a track-oriented open pipe. While not every GR86 APEXi system includes this feature, those that do provide unmatched versatility for daily driving and weekend track days.

Performance Gains: Dyno-Proven Results

Horsepower and Torque Increases

The primary goal of any exhaust upgrade is to improve engine breathing. By reducing exhaust back pressure, the FA24 engine can expel spent gases more efficiently, which in turn allows the intake cycle to draw in a denser air-fuel charge. Multiple independent dyno tests on the GR86 platform show that a cat-back exhaust system, like those offered by APEXi, typically yields gains of 5–8 wheel horsepower and 4–6 lb-ft of torque without any additional tuning. When paired with an aftermarket intake and a professional ECU calibration, these gains can multiply significantly.

Importantly, APEXi designs their exhausts to maximize torque in the mid-range (3,500–5,500 RPM) where the car feels most responsive on the street. This improvement makes the GR86 feel punchier during daily driving, reducing the need to downshift for overtaking maneuvers.

Weight Reduction and Its Effects

Stock exhaust systems are often heavy due to multiple catalytic converters, resonators, and thick-walled piping. The APEXi exhaust system can reduce weight by 10–15 pounds or more, depending on the specific model. This reduction is particularly beneficial on the GR86, as it sits at the rear of the car and influences polar moment of inertia. Lighter weight at the rear improves the car’s ability to rotate into corners and reduces the load on the rear suspension, contributing to sharper turn-in response.

Throttle Response and Drivability

Beyond peak numbers, drivers consistently report a noticeable improvement in throttle response after installing an APEXi exhaust. The reduced back pressure means the engine revs more freely, especially when blipping the throttle for downshifts. The car feels more eager to accelerate, and the engine note synchronizes with throttle inputs in a way that makes the driving experience feel more immediate and connected.

For those who plan to further modify their GR86, the APEXi exhaust provides an excellent foundation for a future tune or even a supercharger kit. The reduced restriction ensures that added boost or higher RPM demands can be met without needing to replace the exhaust a second time.

Sound Characteristics: From Civilized to Aggressive

Cold Start and Idle

One of the first things you’ll notice after installation is the cold start sequence. The APEXi exhaust amplifies the boxer engine’s signature burble, providing a deeper, more purposeful note. At idle, the exhaust settles into a low rumble that is present but not intrusive—a welcome change for those who find the stock exhaust too muted.

Driving Under Load

As you accelerate through the gears, the APEXi system reveals its true character. The sound is aggressive yet refined. There is no high-pitched raspiness; instead, the exhaust produces a deep, rich tone that builds to a satisfying crescendo near redline. The FA24 engine’s natural growl is preserved and enhanced, making every gear change an auditory event.

Cruising and Highway Drone

APEXi has put considerable effort into minimizing interior drone during steady-state cruising. The system is designed to resonate at a frequency that does not create an annoying hum inside the cabin at common highway speeds (60–75 mph). This makes the GR86 a more pleasant daily driver, as long trips are not fatigued by constant exhaust rumble. If you do encounter drone, many owners recommend adding a resonated mid-pipe or keeping the interior silencer installed for the best balance.

Some APEXi cat-back systems include a removable silencer or a valve-controlled baffle. For example, the APEXi N1-X Evolution platform (available for other vehicles) has inspired similar designs for the GR86. With the silencer in place, the exhaust is mellow enough to pass noise ordinances at local tracks. Removing it reveals a more aggressive tone suited for spirited driving or track use. This flexibility is a major selling point for owners who use their car for both commuting and weekend motorsport.

Installation Process and Fitment Considerations

Difficulty and Required Tools

Installing an APEXi cat-back exhaust is a straightforward job that can be completed by a home mechanic with moderate experience. Most installations take 1–2 hours with the right tools. You will need:

  • Jack stands or a lift
  • Socket set (typically 10mm, 12mm, 14mm sockets)
  • Penetrating lubricant (e.g., WD-40 or PB Blaster)
  • Exhaust hanger removal tool (or a flathead screwdriver with patience)
  • Torque wrench

Step-by-Step Overview

  1. Lift the vehicle securely on jack stands, ensuring the rear is high enough to work under.
  2. Remove the stock exhaust. Unbolt the flanges at the mid-pipe and muffler sections. Spray penetrating lubricant on the hangers before attempting to remove them. Use an exhaust hanger tool or a screwdriver to pry the rubber hangers off the studs.
  3. Install the APEXi system. Begin by loosely fitting the mid-pipe section onto the OE front pipe flange. Then attach the rear muffler section, using the supplied gaskets and hardware. Tighten all bolts hand-tight initially, then torque to the manufacturer’s specifications (typically 30–35 ft-lbs for flange bolts).
  4. Reattach the hangers. Slide the rubber hangers onto the new system’s studs. Ensure the exhaust is centered and sitting without contacting any chassis components, driveshaft, or heat shields.
  5. Check alignment and clearance. The tip should sit evenly in the rear bumper cutout. If not, loosen the flange bolts and adjust the angle before final torque.
  6. Start the engine and listen for leaks. A soapy water spray can help identify small leaks at the flanges—tighten any problematic bolts.
  7. Test drive and listen for rattles. Re-check all fasteners after a heat cycle.

Potential Pitfalls

On some early production GR86s, the rear differential housing may be very close to the exhaust path. APEXi designs their systems to clear all factory components, but if you have aftermarket subframe braces or different bushings, double-check clearance. Also, cars with automatic transmissions have slightly different rear floor pan contours—verify that a manual-specific system will fit your automatic if you choose that path. Fortunately, APEXi typically offers separate SKUs for manual and automatic models on the GR86 platform.

Maintenance and Longevity

Keeping the Exhaust Pristine

Stainless steel naturally resists rust, but it can still discolor from heat and road salt. To keep your APEXi system looking good, give it a rinse with a mild automotive degreaser and a sponge whenever you wash the car. Avoid using abrasive scouring pads that can scratch the polished surface. For titanium tips, a dedicated titanium cleaner will help preserve the unique color.

Checking Mounts and Fasteners

Exhaust systems are subject to constant vibration and thermal expansion. Every oil change or at least twice a year, inspect the rubber hangers for cracking and the flange bolts for loosening. Many APEXi systems use lock nuts or spring-loaded bolts to prevent loosening, but it’s good practice to verify. A loose bolt can cause an annoying rattle or even allow the exhaust to shift and contact the underbody.

Managing Internal Buildup

Direct injection engines like the FA24 can produce carbon deposits in the exhaust over time, especially if the car is used primarily for short trips. Consider an occasional high-RPM highway pull to help clear out any accumulated soot. The straight-through design of the APEXi muffler is less susceptible to clogging than chambered designs, but regular high-load runs will keep the sound and flow consistent.

Comparison with Competitors

APEXi vs. Borla

Borla exhausts are known for a deep, mellow tone and their US-made construction. They tend to be quieter than APEXi systems at idle but can become louder under heavy throttle. Borla uses austenitic stainless steel similar to APEXi, but their muffler design often has a more traditional chambered layout. If you want a louder, more aggressive sound with the option to adjust noise level, APEXi is the better choice. For a more refined touring sound, Borla might be preferable.

APEXi vs. HKS

HKS is another Japanese powerhouse, renowned for their Legamax and Hi-Power exhausts. HKS systems are often lighter and more track-oriented, with a higher focus on weight savings and sound volume. APEXi generally offers a more street-friendly experience with less drone and a more balanced tone across the rev range. The APEXi system tends to be a better daily driver, while HKS leans toward the track enthusiast.

APEXi vs. Injen

Injen exhausts are typically more affordable but use lower-grade stainless steel and simpler muffler designs. APEXi’s superior material quality and mandrel-bent construction justify its premium price with better fit and finish, as well as a longer lifespan. If budget is a primary concern, Injen may suffice, but for long-term durability and a proven tuning pedigree, APEXi is the recommended upgrade.

Conclusion: Is the APEXi Exhaust Worth It?

The APEXi exhaust system for the GR86 is more than just a sound mod—it is a performance upgrade that complements the car’s naturally aspirated character. With genuine gains in horsepower and torque, a meaningful reduction in weight, and an exhaust note that respects both neighbors and track rules, this exhaust ticks many boxes for the discerning enthusiast. The quality of materials and engineering ensures that the system will last for the life of the car, making it a sound investment for anyone who plans to keep their GR86 for the long haul.

For daily driving, the APEXi system strikes an excellent balance between spirit and civility. For track use, its straight-through design and optional silencer cater to varying noise regulations and personal taste. When paired with other bolt-on modifications like a cold air intake and a tune, the APEXi exhaust forms the backbone of a responsive, powerful, and sonically thrilling GR86.

If you are ready to transform your GR86’s driving experience, explore the full range of APEXi exhaust systems at their official website: APEXi USA. For real-world dyno results and owner reviews, check out the GR86 section on FT86Club or the popular performance parts retailer Import Image Racing.