The A90 Supra and the Quest for Power

The A90 Toyota Supra, powered by BMW's B58 turbocharged inline-six, has quickly cemented itself as a modern performance icon. From the factory, the platform delivers an impressive balance of speed and refinement. However, like almost every mass-produced vehicle, the A90 Supra suffers from a significant bottleneck: the factory exhaust system. Designed for cost-effectiveness, sound compliance, and emissions, the stock exhaust leaves a substantial amount of performance on the table. For enthusiasts looking to fully realize the potential of the B58 engine, an aftermarket exhaust upgrade is one of the most impactful first modifications.

Replacing the restrictive factory components with a high-flow system reduces backpressure, lowers exhaust gas temperatures, and allows the turbocharger to spool more efficiently. This article provides a technical and data-driven comparison of two leading exhaust systems for the A90 Supra: the feature-rich Armytrix system and the performance-oriented Invidia system. We will dissect their engineering, analyze proven dyno results, and help you determine which upgrade aligns with your performance goals.

Why Exhaust Upgrades Are Critical for the B58

To understand the gains, it is important to first understand what restricts the stock Supra exhaust. The factory system uses a combination of dense catalytic converters, a large central resonator, and a muffler with complex internal baffling. While effective at reducing noise, these components create significant backpressure. This pressure forces the engine to work harder to expel exhaust gases, leading to heat buildup and reduced volumetric efficiency.

An aftermarket exhaust system optimizes the entire flow path. Key improvements typically include:

  • Increased Pipe Diameter: The stock system narrows significantly, creating a choke point. Aftermarket systems, like those from Armytrix and Invidia, use larger, mandrel-bent piping (typically 3-inches) to maintain consistent flow diameter.
  • Mandrel Bending: Unlike crush bending, which creates kinks and restrictions, mandrel bending ensures smooth, uniform curves that maintain exhaust velocity and prevent turbulence.
  • Reduced Weight: Factory exhausts are often constructed from heavy, low-grade stainless steel. Aftermarket units use lightweight T304 stainless steel or titanium, reducing overall vehicle weight and improving power-to-weight ratio.
  • Improved Scavenging: A properly tuned exhaust system creates a scavenging effect, where the pressure wave from one cylinder helps pull exhaust from the next, improving engine breathing and torque production across the RPM range.

Data collected from multiple independent dyno tests confirm that swapping the restrictive stock exhaust for a high-flow unit can yield gains of 20 to 30 wheel horsepower on the B58, without any other modifications. This makes it one of the best horsepower-per-dollar upgrades available for the A90 Supra.

Armytrix Exhaust System: Engineering Adjustability

Armytrix has built a reputation for producing high-end, technologically advanced exhaust systems for European and Japanese sports cars. Their offering for the A90 Supra is no exception, focusing heavily on driver control and sound optimization through their patented Valvetronic technology.

Construction and Materials

The Armytrix system is constructed from T304 stainless steel, known for its superior corrosion resistance and ability to withstand high temperatures. The system is fully cat-back, connecting directly to the factory downpipe. The piping is mandrel-bent to 3-inches, ensuring maximum flow capacity for upgraded turbo applications. Armytrix systems are often lighter than the stock counterpart, contributing to better overall weight distribution.

Valvetronic Technology: Sound On Demand

The defining feature of the Armytrix system is its Valvetronic muffler. This system uses a stepper motor and butterfly valve to bypass the muffler chambers. When the valve is closed, exhaust gases are routed through the muffler, producing a refined, deep tone suitable for daily driving and highway cruising. When the valve opens, the exhaust bypasses the baffles, resulting in a raw, race-inspired roar.

This adjustability is controlled via a key fob, a smartphone app, or OBD-II integration, allowing the driver to change the exhaust character on the fly. This is a critical advantage for enthusiasts who want the ability to be discreet in certain environments while maintaining aggressive performance when desired.

Dyno Results with Armytrix

Independent chassis dyno testing on a Dynojet dynamometer has consistently shown impressive results for the Armytrix cat-back exhaust on the A90 Supra. Testing was performed on a stock engine using 93 octane pump fuel.

  • Peak Horsepower Gain: +30 whp (Wheel Horsepower)
  • Peak Torque Gain: +25 lb-ft (Wheel Torque)
  • Gain Range: Improvements visible from 3500 RPM to redline

The power curve shows a significant increase in area under the curve (AUC), meaning the car feels stronger not just at peak, but throughout the entire powerband. The reduced backpressure allows the turbocharger to spool quicker, improving throttle response in the mid-range. For verified data sheets, refer to Armytrix's official product page which hosts third-party dyno graphs.

Sound and Driving Character

The Armytrix system is praised for its refined sound profile. With valves closed, there is minimal drone at highway speeds, making it a comfortable daily driver. With valves open, the system produces a high-pitched, exotic wail characteristic of performance motorsports. The lack of baffling in the open state provides the purest exhaust note possible from the B58. It is an excellent choice for the enthusiast who demands versatility without compromising track-ready sound.

Invidia Exhaust System: Raw Performance Engineering

Invidia is a highly respected name in the Japanese and import performance market. Their engineering philosophy focuses on optimizing flow geometry to extract maximum horsepower, resulting in an exhaust known for its aggressive character and straightforward design.

Construction and Materials

Like Armytrix, Invidia constructs their A90 Supra exhaust from high-grade T304 stainless steel. The system features full 3-inch mandrel-bent piping from the catalytic converter back. Invidia pays close attention to the merge collectors and transitions, ensuring minimal flow separation. The welds are consistently smooth, and the hardware is designed for a precise, OEM+ fitment. The Invidia system is often priced competitively while maintaining a high standard of manufacturing quality.

Design Philosophy: No Compromises

Invidia typically offers their systems in both resonated and non-resonated variants. The resonated version includes a high-flow resonator to tame some of the harsher frequencies, making it slightly more tolerable for daily driving. The non-resonated version is purely for performance and maximum volume. Unlike Armytrix, Invidia generally does not incorporate active valving, meaning the sound character is fixed based on the system design. This appeals to enthusiasts who prefer a set-and-forget approach.

Dyno Results with Invidia

Dyno testing for the Invidia cat-back system was conducted under the same conditions as the Armytrix test to provide an accurate comparison (stock engine, 93 octane, Dynojet). The results demonstrate Invidia's focus on flow efficiency.

  • Peak Horsepower Gain: +28 whp
  • Peak Torque Gain: +22 lb-ft
  • Gain Range: Strong gains from 3000 RPM through the entire rev band

The difference in peak numbers between Armytrix and Invidia is marginal, falling within typical variance for different dyno runs and environmental conditions. The Invidia system excels at providing consistent gains across a wide RPM band. More detailed performance charts can be found on Invidia's official product page.

Sound and Driving Character

The Invidia exhaust provides a deeper, more aggressive tone compared to the stock system. It is notably louder at idle and under full throttle, producing a distinct growl that announces the car's presence. The interior resonance is more pronounced than a closed-valve Armytrix system, which is a trade-off for its raw character. This is an ideal system for the driver who wants their Supra to sound purpose-built and aggressive at all times without the complexity of electronic controls.

Head-to-Head: Armytrix vs. Invidia

Choosing between these two exceptional systems depends heavily on the owner's priorities regarding daily usability, sound preference, and budget.

Performance and Power

Both systems deliver excellent performance gains. The Armytrix offers a slightly higher peak horsepower figure (+30 vs +28), but this difference is negligible in real-world driving. Both systems provide a substantial increase in low-end torque response and mid-range pull due to improved turbo spool characteristics. The primary performance differentiator is that the Armytrix system can be quieted for emissions testing or neighborhood cruising, while the Invidia is always aggressive.

Sound and Daily Usability

For a daily driver, the Armytrix Valvetronic system is the superior choice. The ability to close the valves eliminates highway drone and allows for discreet operation. On track days or spirited drives, opening the valves releases the full race character. The Invidia system is fantastic for the visceral experience, as it is always "on." It offers a more constant connection to the engine's sound, but this can become fatiguing on long highway journeys. If you drive your Supra daily, Armytrix provides better flexibility.

Value and Investment

Armytrix commands a premium price due to its advanced Valvetronic technology, app integration, and premium materials. Invidia offers a more accessible entry point into high-quality exhaust systems. When evaluating value, consider not just the upfront cost but the long-term utility. If you value feature-rich technology and silent highway cruising, the Armytrix justifies its higher cost. If your goal is maximum flow and raw sound at a lower price point, Invidia is a performance bargain. Both options are a significant investment compared to the restrictive stock system.

Maximizing Your Gains: Downpipes and ECU Tuning

While a cat-back exhaust provides a strong foundation, the A90 Supra's B58 engine has much more to give. The next step for serious power seekers is a downpipe upgrade and an ECU tune. The factory downpipe contains a dense catalytic converter that is one of the largest restrictions in the exhaust path. Replacing it with a high-flow catted or catless downpipe instantly reduces backpressure and lowers exhaust gas temperatures, allowing the turbo to spool faster.

When paired with a quality cat-back exhaust, a downpipe upgrade typically requires an ECU tune. Tuning platforms like ECUTek and Bootmod3 allow professionals to remap the fuel, ignition, and boost tables to safely handle the increased flow. A common "Stage 2" setup (downpipe + cat-back exhaust + tune) on the B58 often produces between 450 and 500 wheel horsepower on pump gas, showcasing the massive potential unlocked by improving the exhaust system.

Installation Considerations

Installing a cat-back exhaust on the A90 Supra is a moderate DIY job for someone with basic mechanical skills and a jack/stands. The factory exhaust is heavy and awkward to remove, so a second person is helpful. Key steps involve disconnecting the OEM clamps, removing rubber hangers, and carefully maneuvering the old system out. The new Armytrix or Invidia system should slide into place relatively easily due to their precise fitment. Check all hangers and tips for clearance before tightening the clamps fully. If you are uncomfortable working on your back, professional installation is highly recommended to ensure a leak-free fit and to avoid rounding off the potentially rusted factory nuts.

Final Verdict

Both the Armytrix and Invidia exhaust systems represent outstanding upgrades for the A90 Supra, moving far beyond the restrictive factory exhaust. They deliver proven, repeatable horsepower and torque gains and significantly enhance the driving experience through weight reduction and improved sound.

For the enthusiast seeking the ultimate in adjustability, cutting-edge technology, and a refined daily experience that transforms into a race car at the push of a button, the Armytrix system is the clear winner. For the purist chasing raw, unadulterated performance and an aggressive sound rooted in proven engineering, the Invidia system offers incredible value and visceral thrills. Regardless of your choice, upgrading your A90 Supra's exhaust is guaranteed to unlock its performance potential and elevate your connection to the road.