The Armytrix GT-R Exhaust System is a premium aftermarket upgrade designed to deliver a significant boost in performance, weight reduction, and an aggressive exhaust note tailored to the Nissan GT-R. Whether you are a seasoned DIY mechanic or an enthusiastic GT-R owner, this comprehensive guide will walk you through each stage of installation with precision. Follow these detailed steps to ensure a leak-free, optimally aligned setup that maximizes the system's potential while maintaining safety and reliability.

Understanding the Armytrix GT-R Exhaust System

The Armytrix GT-R exhaust is engineered from T304 stainless steel and features precision TIG welding, mandrel-bent tubing, and proprietary valve technology (Armytrix SmartBox) for adjustable sound levels. The system includes downpipes, mid-pipes, rear muffler section, and quad exhaust tips. Typical weight savings are around 40–60 lbs compared to the factory exhaust, which improves acceleration and handling. Before starting the installation, familiarize yourself with the kit components and verify that all parts match your GT-R model year (2009–2021 R35).

For official specifications and product details, visit the Armytrix GT-R Exhaust System page.

Tools and Materials Required

Having the correct tools on hand will streamline the installation and prevent frustrating delays. Below is a comprehensive list of what you will need:

  • Socket set (metric: 10mm, 12mm, 14mm, 17mm, 19mm) with extensions and universal joint
  • Wrench set (combination) – 10mm through 19mm
  • Torque wrench – capable of 20–80 ft-lbs (27–108 Nm)
  • Jack and jack stands (or vehicle lift) – minimum 2-ton capacity
  • Exhaust hanger removal tool or long flathead screwdriver
  • Penetrating oil (e.g., PB Blaster or WD-40) for rusted fasteners
  • Wire brush for cleaning flange surfaces
  • Safety goggles and mechanic's gloves
  • Fender covers (optional) to protect paint
  • Pry bar (for stubborn hangers)
  • Anti-seize compound for threads
  • New exhaust gaskets (if not included in kit)

Safety Precautions and Preparation

Work in a well-ventilated area, preferably a garage with the door open. Ensure the vehicle is parked on a level surface and the engine is completely cool. Disconnect the negative battery terminal to avoid accidental electrical shorts, especially if your GT-R has active exhaust valves (Armytrix connects to the factory valve wiring). Wear safety goggles at all times when working under the car – debris, rust, and exhaust soot can fall into your eyes. Never rely solely on a jack; always use jack stands rated for the vehicle's weight (approximately 3,800 lbs for the GT-R).

Before lifting, break free all exhaust fasteners while the car is still on the ground to avoid excessive movement under the vehicle. Apply penetrating oil to flange bolts and rubber hanger mounts 30 minutes prior to removal.

Step 1: Lift the Vehicle

Position the jack at the designated lifting points under the front subframe or the rear differential housing. Raise the vehicle to a comfortable working height (approximately 18–24 inches from the ground to the chassis) and place jack stands under the reinforced jacking points on each side. Gently lower the vehicle onto the stands and confirm stability by shaking the chassis. For additional clearance, you may also lift the front and rear separately, but ensure all four corners are secured.

Step 2: Remove the Stock Exhaust System

Begin at the front of the vehicle. Locate the exhaust flanges where the downpipes meet the turbocharger outlets. Use a 14mm socket and extension to remove the four bolts on each flange. If the bolts are seized, apply heat carefully with a propane torch (avoid touching rubber lines). Once the downpipe bolts are free, slide them out.

Move to the mid-pipe connections. The GT-R stock exhaust has multiple joints secured with 12mm bolts and spring-loaded nuts. Remove all hardware and set aside. Use the exhaust hanger removal tool or a flathead screwdriver to pry the rubber isolators off the metal hanger posts. Work from the rear forward: first detach the muffler section, then the mid-pipes. Lower each section gradually, supporting the weight to avoid damage to the hangers or sensors. Be careful of oxygen sensors (if your model has them in the stock exhaust) – disconnect the wiring harness clips before removal.

With the entire stock exhaust removed, inspect the undercarriage for any damaged heat shields or loose brackets. Clean the flange surfaces with a wire brush to remove rust and old gasket material. Install the new exhaust gaskets provided in the Armytrix kit.

Step 3: Install the Armytrix GT-R Exhaust System

The Armytrix system is modular and typically starts with the downpipes. Position the downpipes onto the turbo flanges, ensuring the gaskets are aligned. Hand-tighten the bolts first, then torque to 35–40 ft-lbs (47–54 Nm) using a cross pattern. Next, attach the mid-pipe section by sliding the flanged ends together. Use the supplied stainless steel clamps or bolts; do not fully tighten until the entire system is mocked up.

Install the rear muffler section last. Lift it into place and attach it to the mid-pipes. Secure the exhaust hangers onto the rubber mounts. Armytrix systems often use polyurethane hanger bushings for extra vibration dampening. Apply a small amount of soapy water to ease installation. Ensure the exhaust tips are centered within the rear bumper cutouts. Adjust the position of the muffler by loosening the mid-pipe clamps and sliding the pipes until both tips are symmetric with the bumper.

If your Armytrix system includes an active valve controller (SmartBox), connect the valve wiring to the factory actuator harness. Follow the included wiring diagram; usually it splices into the 12V power and ground leads. Secure any excess wiring with zip ties to avoid heat contact.

For more installation tips and torque specifications, refer to the Armytrix installation guide library.

Step 4: Tighten All Connections

Once the entire system is in place and aligned, begin tightening all hardware to manufacturer torque specifications. Use the following typical values (verify with your kit manual):

  • Downpipe-to-turbo flange bolts: 35–40 ft-lbs
  • Mid-pipe clamp bolts: 30–35 ft-lbs
  • Muffler hanger bolts: 15–20 ft-lbs
  • Exhaust tip set screws: 10–12 ft-lbs

Apply anti-seize compound to all threaded fasteners to facilitate future removal. Double-check that all clamps are oriented so that the bolts are accessible for future adjustments.

Step 5: Check for Leaks

With everything torqued, start the engine and let it idle for 2–3 minutes to warm the exhaust. Have a helper listen for hissing or popping sounds at each joint while you inspect under the car using a handheld mirror. Alternatively, you can use a smoke machine or soapy water spray (bubbles indicate leaks). Pay special attention to the downpipe flanges and the mid-pipe slip joints. If a leak is detected, shut off the engine and tighten the affected bolts or clamps slightly, but do not over-torque as this can distort flanges.

Step 6: Final Adjustments and Test Drive

After verifying no leaks, turn off the engine and perform a final check of hanger alignment and tip position. Cycle the active valves (if applicable) using the remote or smartphone app to ensure full range of motion. Lower the vehicle from the jack stands and reconnect the battery.

Take the GT-R for a short test drive in a safe area. Gradually accelerate through 2nd and 3rd gears while varying the RPM between 2,000 and 5,000. Listen for any rattles or vibrations against the chassis. If you hear metallic contact, it may indicate that a pipe is too close to a heat shield or crossmember. Minor adjustments can be made by loosening clamps and shifting the pipes. Re-tighten after alignment. Some slight settling is normal during the first heat cycle; recheck all bolts after 100 miles of driving.

Tuning and ECU Considerations

Installing a free-flowing exhaust system like the Armytrix changes the backpressure and exhaust gas velocity, which may affect air-fuel ratios. On a stock GT-R, the factory ECU can often compensate within safe limits. However, to fully unlock the performance gains, a professional ECU tune (e.g., Cobb Accessport or Ecutek) is strongly recommended. Tuning also allows you to optimize the valve timing and eliminate the check engine light that may appear if oxygen sensors are relocated. Consult a reputable Nissan GT-R tuner before adding other modifications.

Learn more about GT-R tuning considerations at GTR Heritage Exhaust & Tuning Guide.

Common Issues and Troubleshooting

CEL (Check Engine Light) After Installation

If the check engine light illuminates, it is often due to an oxygen sensor that is not fully seated or wiring damage during installation. Scan the vehicle with an OBD-II reader to identify the code. Common codes include P0420 (catalyst efficiency) – this may require an oxygen sensor spacer or a tune to bypass. Ensure all sensor connectors are clean and locked.

Exhaust Rattle at Idle

Rattles usually indicate contact between the exhaust pipe and the underbody brace, driveshaft, or heat shield. With the car safely lifted, inspect the line between each pipe and the chassis. Use a rubber mallet to gently tap the pipe away from the contact point. If necessary, insert a thin piece of rubber or silicone between the pipe and the chassis (avoid using metal spacers as they may transmit noise).

Valves Not Opening/Closing

For Armytrix SmartBox systems, verify the wiring connections and ensure the fuse is intact. The app or remote should show the valve position. If valves remain stuck, check the actuator linkage for binding and lubricate with silicone spray. In rare cases, the spring inside the actuator may have dislodged during shipping – contact Armytrix support for a replacement.

Maintenance Tips

To keep your Armytrix exhaust looking and performing its best:

  • Clean the exhaust tips regularly with a non-abrasive metal polish to prevent tarnishing (titanium tips may develop a golden heat stain, which is normal).
  • Inspect all clamp bolts and hanger bolts for loosening every 5,000 miles – retorque as necessary.
  • Periodically lubricate the valve actuator linkage with a high-temperature grease.
  • If you drive in winter conditions, apply a rust inhibitor to the stainless steel welds (though T304 is highly corrosion-resistant).
  • When washing the undercarriage, avoid pressure-washing directly onto the valve motors.

Conclusion

Installing the Armytrix GT-R Exhaust System is a rewarding upgrade that dramatically improves the driving experience through weight reduction, increased horsepower, and a customizable exhaust note. By following this step-by-step guide and paying close attention to alignment, torque specs, and electrical connections, you can achieve a professional-quality installation at home. Always adhere to safety protocols and do not hesitate to consult a professional if you encounter stubborn hardware or complex wiring. Once completed, enjoy the unmistakable sound and performance of your Armytrix-equipped GT-R.

For further community support and technical discussions, visit the GT-R Life forum’s Armytrix exhaust thread.