Installing a COBB Tuning Cat-Back exhaust system on your Toyota GR86 is one of the most rewarding upgrades you can make. It delivers a deeper, more aggressive exhaust note, reduces weight, and improves exhaust flow for a modest performance gain. While the process is straightforward for a DIY enthusiast with basic tools, attention to detail ensures a leak-free, rattle-free fit that will last for years. This guide expands on the core steps with detailed tips, torque values, safety practices, and post-installation advice so you can tackle the job with confidence.

Why Choose the COBB Tuning Cat-Back Exhaust?

The COBB Tuning Cat-Back system is engineered specifically for the Subaru BRZ / Toyota GR86 platform. It features mandrel-bent 304 stainless steel tubing, a straight-through muffler design, and precision TIG welding for durability. The result is a noticeable improvement in throttle response and a rich sound that avoids drone on the highway. For drivers looking to combine performance with daily-driver civility, the COBB exhaust is a proven choice. You can read more about the system’s specifications on the COBB Tuning official site.

Tools and Materials Needed

  • COBB Tuning Cat-Back Exhaust System (complete kit with hardware)
  • Socket set: 14mm, 17mm sockets (and extensions for hard-to-reach bolts)
  • Ratchet with extension bars (6-inch and 12-inch recommended)
  • Torque wrench (capable of 30–50 lb-ft range)
  • Jack and pair of jack stands (or ramps + stands for extra height)
  • Safety glasses and mechanic’s gloves
  • Penetrating oil (e.g., WD-40 Specialist or Liquid Wrench)
  • Pry bar or trim removal tool (for stubborn rubber hangers)
  • Optional but recommended: anti-seize compound, new exhaust gasket (check condition of flange gasket), shop rags, and a floor creeper

Having these tools on hand before you start prevents mid-job frustration. If you are new to using a torque wrench, consult a reliable torque wrench guide to learn proper calibration and handling.

Safety First: Preparing Your Workspace

Work in a well-ventilated area with plenty of light. A flat concrete floor is ideal; avoid gravel or dirt surfaces. Before lifting the car, chock the rear wheels (if lifting the front) or front wheels (if lifting the rear). Never get under a vehicle supported only by a jack—always use jack stands rated for your vehicle’s weight. The GR86 curb weight is around 2,800 lb, so a pair of 3-ton stands provides a generous safety margin. Wear safety glasses to protect against falling debris and gloves to guard against sharp edges and hot components if the engine has been run recently.

Pre-Installation Checks

Start with a cold exhaust system. If you have just driven the car, let it cool for at least an hour. Examine the stock exhaust to note how the hangers and flanges are oriented—take photos for reference. Spray all bolts you’ll be loosening (manifold-to-midpipe bolts, hanger bolts if present, and any support bracket hardware) with penetrating oil. Allow the oil to soak for 10–15 minutes while you prepare the new exhaust. Unbox the COBB system and verify all components are present: the front pipe section, axle-back section, gaskets, spring bolts, and any clamp hardware. Read the included instructions thoroughly, as COBB often provides specific torque values.

Step 1: Lift and Secure the Vehicle

Position the jack under the rear differential or designated jack point at the rear of the car. Raise the vehicle until the rear wheels are about 18 inches off the ground. Place jack stands under the reinforced jack points behind the front wheels or under the rear subframe, depending on your workspace. Gently lower the car onto the stands and give it a shake to confirm stability. If using ramps, drive up slowly and then supplement with jack stands as a backup. Ensure the parking brake is engaged.

Step 2: Remove the Stock Exhaust

2a. Loosen the Bolts at the Main Flange

Locate the flange connecting the catalytic converter (or front pipe) to the stock cat-back. Typically, this uses two 14mm bolts or nuts. Apply more penetrating oil if they resist. Use a combination of ratchet, extension, and a breaker bar if necessary. Apply steady force to avoid rounding the fasteners. Once loose, remove them completely. The exhaust will now hang only from the rubber hangers.

2b. Disconnect the Rubber Hangers

There are usually four or five rubber hangers along the center and rear of the exhaust. Spray them with silicone lubricant or soapy water to ease removal. Use a pry bar or a dedicated hanger remover tool to push the metal peg out of the rubber mount. Work from the rear forward. If a hanger is stuck, rock the exhaust section side-to-side to break it loose. It may help to have a second person hold the exhaust while you free the last few hangers. Lower the stock exhaust carefully—it is long and heavy. Slide it out from under the car.

2c. Inspect the Midpipe Gasket

The factory gasket at the flange is often reusable if it is in perfect condition, but many installers prefer to replace it with a new one (COBB supplies gaskets in the kit). Check the mating surfaces on the front pipe for rust or carbon buildup. Clean them with a wire brush or scuff pad to ensure a good seal later.

Step 3: Prepare the COBB Cat-Back for Installation

Before sliding the new exhaust under the car, loosely assemble the sections (front and rear) if they come separate. Lightly apply anti-seize to the threads of any bolts that will be used at stainless-to-stainless connections to prevent galling. Insert the supplied spring bolts into the flange—these are designed to allow some flex and reduce vibration-induced loosening. Position the included gaskets between each mating surface. Do not tighten anything yet; you want the system to be loosely connected so it can move for alignment.

Step 4: Install the COBB Cat-Back Exhaust System

4a. Lift the Assembly into Place

With the help of a friend or a transmission jack, lift the COBB exhaust into position under the car. Align the front flange with the catalytic converter output flange. Insert the new gasket and loosely thread the spring bolts by hand. Ensure the system is angled so the hanger pegs align with the rubber mounts. It is easier to start the hangers from the front and work toward the rear.

4b. Attach Rubber Hangers

Slide each rubber hanger mount onto its corresponding metal peg. If the rubber is too tight, apply a dab of silicone lubricant. Check that each hanger is fully seated on the peg. The COBB system uses high-quality hangers; make sure none are twisted. After all hangers are installed, adjust the exhaust so it hangs centrally in the chassis tunnel—clearance to the heat shield, rear sway bar, and differential should be at least 0.5 inches on all sides. Rotate the tips to center them in the bumper cutouts.

4c. Tighten All Fasteners to Spec

Once the system is aligned and hangers are secure, begin tightening the flange bolts. Use a torque wrench. COBB typically calls for 30–35 lb-ft on the 14mm spring bolts. Tighten in a crossing pattern to ensure even compression of the gasket. Avoid over-tightening, as it can warp the flange or strip the threads. For any clamp connections (if your system includes slip joints), use a 15mm socket and tighten to 25–30 lb-ft or as specified.

Step 5: Check for Leaks and Rattles

Start the engine with the car still on jack stands so you can easily access all connections. Let it idle for 60 seconds, then rev gently to 2,000–3,000 RPM. Listen for any hissing or popping sounds that indicate a leak at the flange. Place your hand near each joint (careful of hot surfaces) to feel for escaping gasses. If you detect a leak, shut off the engine, allow it to cool, and tighten the fasteners an additional 2–3 lb-ft. Never exceed the maximum torque. Also listen for metallic rattles—if the exhaust contacts the underbody or heat shield, you may need to bend a heat shield tab slightly or reposition a hanger.

Step 6: Lower the Vehicle and Test Drive

Once satisfied that there are no leaks and the system is quiet, carefully lower the car using the jack. Remove the jack stands and lower completely. Tighten the lug nuts to 89 lb-ft (torque to spec). Take the car for a 10-minute test drive, varying engine speeds. Let the system cool, then recheck all flange bolts and hanger positions. It is normal for the bolts to need a slight retorque after the first heat cycle. The exhaust will settle and the sound will deepen after about 100 miles of driving.

Post-Installation: Break-In Period and Sound Character

The COBB Cat-Back exhaust will continue to change tone over the first 500 miles as carbon builds up inside the muffler and packing settles. Initially, the sound may be slightly louder than expected, but it will mellow into a refined, aggressive note. Expect a deep growl at low RPM and a sporty howl near redline. There is no significant drone on the GR86—one of the system’s design strengths. For driving enthusiasts, the weight savings (approx. 10–12 lb compared to stock) also contributes to a more responsive feel. Check out the GR86 Forum for owner reviews and sound clips to confirm your expectations.

Maintenance Tips

  • Inspect the exhaust bolts and hangers every oil change. Retorque as needed, especially in the first 1,000 miles.
  • Keep the stainless steel polished with a quality metal cleaner to prevent discoloration from road grime and heat.
  • If you live in a region with harsh winters, spray the exhaust with a corrosion inhibitor annually, but avoid coating the tips if you want the blue-tinted finish to remain visible.
  • When upgrading other components (downpipe, headers, intake), ensure the cat-back connections remain sealed—always replace gaskets when loosening flanges.

Conclusion

Installing a COBB Tuning Cat-Back exhaust on your GR86 is a well-deserved upgrade that enhances both the sound and driving experience. By following this expanded guide—using proper tools, prioritizing safety, aligning the system carefully, and performing thorough leak checks—you ensure a professional-quality installation that will bring enjoyment for thousands of miles. For further tuning options and to pair your new exhaust with a COBB Accessport or intake, visit COBB’s website and explore the full ecosystem of performance parts designed for your GR86. Your car’s new voice is just a few simple steps away—get out there and enjoy the drive.