Installing a Namzu exhaust system on your GR86 is one of the most rewarding upgrades you can make to your car. Not only does it sharpen the throttle response and free up a few extra horsepower, but it also transforms the driving experience with a richer, more aggressive exhaust note. The Namzu system is engineered specifically for the GR86 platform, using mandrel-bent tubing and quality welds to ensure a perfect fit and long-lasting durability. This guide walks you through every step—from gathering tools to performing the final leak check—so you can complete the installation safely and confidently in your own garage.

Tools and Materials Needed

Before you roll under the car, assemble everything you’ll need. Having the right tools on hand saves time and prevents frustration. Here’s a complete list:

  • Namzu exhaust system – Verify all components (mid-pipe, axle-back sections, gaskets, hardware) are present.
  • Socket set – 10mm, 12mm, 14mm, and 17mm sockets are most common for exhaust bolts.
  • Wrench set – Combination wrenches for tight spaces where a socket won’t fit.
  • Jack and jack stands – A low-profile jack works best; use at least two stands for rear lift.
  • Exhaust hanger removal tool – Optional but highly recommended; a pry bar or needle-nose pliers can also work.
  • Torque wrench – ⅜-inch drive, capable of 20–60 ft-lb range.
  • Penetrating oil – Spray on rusty nuts/bolts 15 minutes before removal.
  • Safety glasses and gloves – Protect eyes from debris and hands from sharp edges.
  • Rubber mallet – Helps loosen stubborn hangers without damaging components.
  • Shop rags or paper towels – Clean mating surfaces before installation.

If you’re working on a lifted GR86 or have access to a car lift, you can skip the jack stands. For home mechanics, always prioritize stability.

Preparation Steps

Good preparation sets the stage for a smooth install. Park the vehicle on a level concrete floor, engage the parking brake, and let the engine cool completely—hot exhaust components can cause burns and are harder to handle. If you’ve just driven the car, wait at least 30 minutes.

Safety First

Never rely on a jack alone to support the car. Use jack stands rated for the vehicle’s weight (GR86 curb weight ~2,800 lbs). Place them under the designated lift points: the rear subframe or reinforced pinch welds. Chock the front wheels to prevent rolling. Wear safety glasses during any under-vehicle work, and gloves when handling exhaust parts that may have sharp edges or carbon deposits.

Inspect the Stock Exhaust

While the car is still on the ground, take a moment to look at the factory exhaust. Note how the hangers are positioned and where the bolts attach. This mental map will make removal quicker. If your GR86 has any corrosion on the exhaust flanges, spray penetrating oil now.

Step 1: Lift the Vehicle

Position the jack at the center of the rear subframe or at the reinforced jack point behind the front wheel (depending on your preferred lift method). Raise the rear until you can slide jack stands under the designated lift points. Lower the car onto the stands and give it a firm shake to confirm stability. The rear wheels should be off the ground by 6–10 inches, giving you enough clearance to work comfortably.

Step 2: Remove the Stock Exhaust System

Start at the front connection to the catalytic converter. Using a 14mm socket, remove the two bolts that hold the stock mid-pipe to the cat. If they’re tight, apply penetrating oil and let it soak for a minute. Next, work your way back: remove the bolts at the mid-pipe to axle-back joint (usually 12mm or 14mm).

Now address the exhaust hangers. The factory system uses rubber isolators that slide over metal hanger rods. Using an exhaust hanger removal tool (or a long flathead screwdriver), pry the rubber loops off the hanger studs. A spray of silicone lubricant on the rubber makes this step easier. You may need to wiggle the exhaust side to side as you work each hanger free. With all hangers released and bolts removed, carefully lower the stock exhaust from the vehicle. Have a helper hold one end if possible; the system is long and can swing unexpectedly.

Step 3: Install the Namzu Exhaust System

Before lifting the Namzu into place, compare it to the stock unit to confirm orientation. Note that the Namzu system may have a different hanger layout—refer to the provided diagram.

Apply Gaskets and Hardware

Many Namzu systems include new gaskets. Place a gasket between the mid-pipe flange and the catalytic converter flange. Do the same for the joint between the mid-pipe and axle-back sections. Hand-thread the bolts to hold everything loosely, making alignment easier.

Hang the System

With the exhaust supported (you can use a jack or a helper), start hooking the rubber isolators onto the Namzu hanger rods. This is often easier if you lubricate the rubber slightly. Begin at the front hanger and work toward the rear, ensuring each isolator seats fully. Once all hangers are in place, tighten the bolts hand-tight using a socket. Do not fully torque yet; you want some play to adjust final positioning.

Step 4: Torque the Bolts

With the system aligned and hanging freely, torque each bolt to the manufacturer’s specification. For the Namzu system, typical values are:

  • Catalytic converter to mid-pipe: 30–35 ft-lb
  • Mid-pipe to axle-back: 25–30 ft-lb
  • Support bracket bolts (if any): 20–25 ft-lb

Use a torque wrench to avoid over-tightening, which can strip threads or warp flanges. Work in a diagonal pattern for flanges with multiple bolts to ensure even clamping pressure. After torquing, double-check that the exhaust tips are centered in the bumper cutouts.

Step 5: Check for Leaks

Lower the car off the jack stands and onto the ground. Start the engine and let it idle. Listen for any hissing or ticking sounds at the flanges. If you suspect a leak, carefully (with a gloved hand) feel around each joint for escaping air—or use a spray bottle with soapy water; bubbles indicate a leak. If leaks are present, shut off the engine, allow the system to cool, and re-torque the affected bolts. Persistent leaks may require a new gasket or slight repositioning of the connecting pipes.

Step 6: Lower the Vehicle Completely

Once leak checks are complete and you’re satisfied with the fit, remove the jack stands and lower the car fully. Re-check the exhaust clearance around the rear bumper, differential, and heat shields. The Namzu system should not touch any part of the chassis.

Step 7: Final Inspection

Give the entire exhaust a visual once-over. Confirm:

  • All hangers are engaged securely and not stretched or torn.
  • Tips are centered and level left to right.
  • No bolts are missing or loose.
  • The exhaust does not rattle against the underbody at idle or when you rev the engine.

Take a short test drive, then re-inspect the flanges for leaks (listen for change in tone). After the first heat cycle, it’s wise to re-torque all bolts after 100 miles as the gaskets settle.

Performance and Sound: What to Expect

The Namzu exhaust is designed to provide a sporty tone without being obtrusive on the highway. Expect a deeper idle and a pronounced howl above 4,000 RPM. Many owners report a slight improvement in throttle response and a 3–5 horsepower gain at the wheels when paired with a tune. The system is TIG-welded and uses 2.5-inch mandrel-bent tubing for optimal flow.

Additional Tips for a Flawless Install

Break-In Period

New exhaust systems need a short break-in. The sound will mellow slightly over the first 200 miles as the packing material settles. Do not be alarmed if the system seems loud initially.

Dealing with Rusty Hardware

If you live in a salt-belt region, stock bolts may be seized. Apply penetrating oil the night before, and use a 6-point socket to avoid rounding. If a bolt snaps, you may need an extractor kit or professional help.

Check for Clearance

After installation, bounce the rear of the car to simulate suspension travel. Ensure the exhaust does not contact the sway bar, control arms, or spare tire well.

Troubleshooting Common Issues

  • Exhaust drone at cruising speeds: Some resonance is normal. If drone is excessive, check that all hangers are properly installed and the system does not touch the chassis.
  • Leak at flange joint: Ensure gaskets are positioned correctly and bolts are torqued evenly. Use new gaskets if reusing old ones.
  • Tips off-center: Loosen the axle-back bolts, adjust tip position, then re-torque.

For more detailed troubleshooting, the Namzu website offers support resources and installation videos. The GR86 Owner’s Forum is also a valuable community where members share tips and photos of their installs.

Conclusion

Installing a Namzu exhaust system on your GR86 is a weekend project that rewards you with immediate acoustic and performance improvements. By following this step-by-step guide—from proper vehicle lifting to final leak checks—you can complete the job with confidence. Take your time on the hangers and torque specs, and don’t hesitate to consult the Namzu installation support page if you run into any snags. Your GR86 will thank you with a voice as sharp as its handling.