Introduction: Why Upgrade the BRZ FA20 Exhaust

The Subaru BRZ (and its Toyota 86/Scion FR-S sibling) with the FA20 engine is a platform built for driving engagement. The factory exhaust system, while adequate, is designed to meet noise regulations and cost targets, often leaving the engine feeling choked and the sound too subdued. Swapping to an Invidia cat-back exhaust system is one of the most popular first modifications because it unlocks a more aggressive exhaust note, reduces backpressure slightly for potential power gains, and sheds weight. This guide provides a detailed, step-by-step walkthrough for installing the Invidia cat-back on your BRZ FA20, covering everything from tool prep to final sound checks. Whether you are a first-time DIYer or an experienced mechanic, following these instructions will ensure a clean, leak-free installation that transforms the character of your car.

Tools and Materials Needed

Before you start wrenching, gather all necessary tools and components. Running back and forth for that missing socket is frustrating and wastes time. Here is a comprehensive list:

  • Invidia Cat-back Exhaust System – Confirm you have the correct model for the BRZ FA20 (N1, Q300, or Gemini – steps are similar). Verify all included hardware: bolts, nuts, gaskets, and hangers.
  • Socket Set – Metric sockets: 10mm, 12mm, 14mm, and 17mm are common for the BRZ exhaust flanges and hanger bolts.
  • Torque Wrench – Essential for tightening flange bolts to spec and preventing overtightening that strips threads.
  • Jack and Jack Stands – A low-profile floor jack and at least two quality jack stands rated for >3,000 lbs.
  • Penetrating Oil – WD-40 or, better, PB Blaster or Liquid Wrench to help free rusted hardware.
  • Breaker Bar or ½" Ratchet – Factory bolts can be stubborn; extra leverage helps.
  • Exhaust Hanger Removal Pliers – A dedicated tool makes pulling rubber hangers off the studs much easier.
  • Safety Glasses and Gloves – Always protect your eyes and hands from dirt, debris, and sharp edges.
  • Rags and Socket Extensions – For wiping grease and reaching tight spaces.
  • Anti-Seize Compound – Apply to threads when reassembling to simplify future removal.

Having everything laid out on a bench or towel ensures you don’t lose small parts under the car.

Preparing Your Vehicle for the Install

Proper preparation prevents problems. Begin by parking on a flat, solid surface. If your driveway is sloped, find a level concrete pad. Engage the parking brake firmly.

If the engine has been running, allow the exhaust system to cool completely. Hot pipes can cause severe burns and make hardware removal harder (heat expands metal). Let it sit for at least 30 minutes; longer is safer.

Next, gather safety gear and lay down a creeper or moving blanket if you plan to slide under the car. Clear the area of tripping hazards. Lift the rear of the car using the jack on the factory-recommended lifting point behind the rear jack point (consult your owner’s manual). Position jack stands under the rear frame rails or pinch welds with rubber pads. Gently lower the car onto the stands and give it a firm shake to confirm stability. The exhaust system runs centrally, so having the rear wheels off the ground gives you ample clearance to work – but you can also work with the car on ramps if you prefer. I recommend stands for maximum workspace.

Safety Note: Never Work Under a Car Supported Only by a Jack

This cannot be overstressed. Use jack stands rated for your vehicle’s weight. The exhaust removal does require some force; the car must be solidly supported.

Removing the Stock BRZ Exhaust System

With the car safely raised, you now have access to the entire rear exhaust system. The factory cat-back consists of two sections: the mid-pipe (with resonator) and the axle-back muffler section. They are connected by a bolted flange and rubber hangers.

Step 1: Apply Penetrating Oil

Spray penetrating oil generously onto all exhaust flange bolts, donut gasket bolts (where mid-pipe meets the catalytic converter front pipe), and the rubber hanger mounts. Give it 5-10 minutes to soak in. This makes removal far less frustrating, especially on older cars with corrosion.

Step 2: Remove Hanger Rubber Isolators

Start by pulling the rubber hangers off the metal studs on the factory exhaust. The BRZ typically has four hangers: two on the mid-pipe, two on the muffler. Use hanger removal pliers or pry with a flathead screwdriver (carefully). Lubricating the inside of the rubber with soapy water or silicone spray makes them slide off easier. Alternatively, you can leave them and remove the entire assembly including hangers – but removing them first frees up movement.

Step 3: Unbolt the Flanges

Now, locate the flange connecting the cat-back to the front pipe (just behind the rear axle). Use a 14mm socket and ratchet. You may need a socket extension to reach. If bolts are very tight, use a breaker bar. Remove both nuts and washers; you can leave the flange bolts (studs) in the front pipe if they are tight. Don’t lose the gasket – you may reuse it if it’s in good condition, though the Invidia kit usually includes a new one.

Next, unbolt the mid-pipe to muffler flange (12mm or 14mm) if your BRZ has a separate mid-pipe section (this varies by model year). Many aftermarket cat-backs (like Invidia) are a single piece or two pieces – but you are removing the stock assembly, so follow the factory joints.

Step 4: Remove the Stock Exhaust

With all hangers disconnected and flanges unbolted, the stock exhaust should be free. You may need to wiggle it from side to side and pull it back. It can be heavy, so have an assistant or support it with a jack stand as you work it loose. Lower the stock exhaust to the ground. It may scrape against the rear differential or axle, but it will slide out toward the rear. Depending on clearance, you might need to tilt the muffler to clear the spare tire well. Once out, set it aside. Inspect the rubber hangers for cracks; if they are brittle, replace them with new OEM or aftermarket ones.

Optional: Remove the Donut Gasket

The factory front pipe to mid-pipe connection uses a donut gasket (graphite ring). If you are not disturbing this joint, leave it untouched. Invidia cat-backs typically reuse this connection with a flat gasket, so you will need to unbolt the donut flange to separate the front pipe from the mid-pipe. Consult your specific kit instructions. On most BRZs, the Invidia mid-pipe has a 3-bolt flange that mates to a 3-bolt front pipe – the donut connection is replaced entirely. Follow your kit.

Installing the Invidia Cat-back Exhaust System

Now the fun part: hanging the new system. Take your Invidia exhaust out of the packaging and arrange the pieces on the floor. Verify you have all sections, clamps, gaskets, and hardware. The type (Invidia N1 single exit, Q300 dual exit, or Gemini) will change the layout slightly, but the general process is the same.

Step 1: Pre-Assembly (if applicable)

Some Invidia cat-backs come in two sections: a mid-pipe and an axle-back. Slide the two together loosely first, but do not tighten. You want to align everything as a unit before torquing.

Step 2: Install Gaskets and Hang the Exhaust

Place the new gasket (included) onto the front pipe studs. If your kit uses a donut gasket adapter or flat 3-bolt flange, follow the included instructions. Lift the Invidia mid-pipe/muffler assembly carefully into position under the car. Start with the mid-pipe connection to the front pipe. Thread the nuts (or bolts) onto the studs, leaving them finger tight. Do not tighten fully yet.

Next, slide the rubber hangers onto the metal studs on the Invidia exhaust. If the hangers are very tight, use a bit of dish soap or silicone spray. Ensure each hanger is fully seated. The Invidia system typically uses the factory hanger locations. Double-check that the tips clear the rear bumper cutouts properly. Adjust the muffler angle and tip depth before final tightening.

Step 3: Tighten All Hardware to Torque Specifications

Once you are satisfied with the alignment (exhaust tips centered in the bumper cutouts, pipes not contacting any chassis or heat shields), begin tightening. Use a torque wrench for accuracy. Typical exhaust flange torque for 8mm studs is around 25-35 ft-lbs; for 10mm studs, 30-40 ft-lbs. Invidia often recommends 35 ft-lbs. Do not overtighten: exhaust studs can snap. Work around the flange in a star pattern. If your system uses spring bolts (like OEM GS300/Supra), but Invidia typically uses regular bolts/nuts. After tightening the front flange, move to the mid-pipe/muffler junction clamp or flange. Torque those similarly.

Step 4: Re-check Hanger Alignment

With everything tight, check that rubber hangers are not twisted or stretched abnormally. Also confirm no part of the exhaust touches the undercarriage, subframe, or rear differential. Shake the exhaust lightly – it should have slight movement but not rattle. If you hear contact, adjust the hanger position or add small heat shield spacers (if needed).

Final Checks and Sound Test

Lower the car off the jack stands completely. Start the engine and let it idle. Immediately listen for any obvious leaks (hissing, puffing sounds) from the flange connections. A small puff at the flange can be fixed by tightening a bit more or checking the gasket.

Let the engine reach operating temperature (a few minutes). Then, gently rev the engine to 2000-3000 RPM and listen from behind the car. The Invidia system will sound deeper and louder than stock – this is normal. If you hear a metallic rattling, shut the engine down and check clearance points (likely a pipe contacting the chassis, axle, or heat shield). Use a pry bar to gently bend heat shields away if necessary.

Finally, go for a test drive. Start with low speeds and build up. Note any drone at specific RPMs (typical with cat-back exhausts, especially axle-backs). The Invidia Q300 is known for moderate drone, while N1 can be louder. The Gemini is more refined. All are subjective. Enjoy the new soundtrack.

Troubleshooting Common Installation Issues

  • Difficult Bolt Removal: If bolts are seized, apply more penetrating oil, tap with a hammer, and use a breaker bar. If a stud breaks, you will need to extract it (use a stud extractor set). Consider replacing with new hardware from a dealer or hardware store.
  • Leaking at Flange: Ensure gasket is centered and flange surfaces are clean. Tighten evenly. If leak persists, you may need a new gasket or the flanges may be warped (rare).
  • Exhaust Tips Off-Center: Loosen the axle-back clamps, adjust the tip angle, and retighten. Some Invidia systems have slotted hangers for adjustment.
  • Rattle / Vibration: Check clearance again. The mid-pipe can hit the rear differential brace or the sway bar. A small bit of aluminum tape or a minor heat shield tweak often fixes it.
  • Check Engine Light: A cat-back alone will not trigger a CEL. If you removed secondary catalytic converters (i.e., if you installed a full turbo-back or downpipe with cat-delete), you could get a CEL. Cat-back is safe.

Performance and Sound Expectations

The primary gains from a cat-back on a naturally aspirated FA20 are modest – typically 5-10 hp and similar torque, mostly at higher RPM. The bigger improvement is sound and weight reduction (the Invidia N1 saves about 6-8 lbs versus the stock muffler). The exhaust note gains a deeper, more aggressive tone. The N1 is very loud, especially with aftermarket headers. The Q300 offers a deeper but more civilized note with less drone. The Gemini is a twin-tip high quality sound that many daily drivers prefer. Choose based on your tolerance for noise and local decibel limits. For more info, check this comprehensive FT86 Club sound comparison thread.

Maintenance Tips for Your New Exhaust

After installation, maintain your Invidia exhaust to keep it looking and sounding great. Use high-temperature exhaust polish or ceramic coating to prevent premature rust. Periodically check the flange bolts and hanger condition – vibration can loosen hardware over the first few hundred miles. Re-torque after 500 miles. If your car sees winter roads, regular washing underneath is important. Some users also remove and re-grease the rubber hangers annually with silicone grease to extend their life.

For further reading on exhaust systems and tuning, visit dedicated Subaru BRZ forums like GR86.org or FT86 Club. Manufacturer details are also on the Invidia website: Invidia USA.

Conclusion

Installing an Invidia cat-back exhaust on your BRZ FA20 is a rewarding weekend project that immediately upgrades the driving experience. With the right tools, patience, and attention to detail, you can achieve a professional-grade installation in your home garage. The sound and power delivery transformation is one of the best value modifications for this platform. Follow the torque specs, take your time with alignment, and enjoy the new character of your car. Remember to obey local noise ordinances and enjoy the soundtrack responsibly.