How to Install Brz Headers: Tips for a Smooth Upgrade Process

What Are BRZ Headers and Why Upgrade?

Headers replace the factory exhaust manifold to improve exhaust gas evacuation from the engine. The stock manifold on a Subaru BRZ (and its Toyota 86/Scion FR‑S siblings) uses a log-style design that creates backpressure and restricts flow. Upgraded aftermarket headers use equal-length primary tubes that optimize scavenging and reduce exhaust pulse interference. The result is a measurable gain in horsepower (typically 10–20 hp) and torque, especially in the mid-to-upper rpm range. Additionally, headers contribute to a more aggressive exhaust note without increasing cabin drone when paired with a proper cat-back system.

Materials vary from 304 stainless steel to mild steel with ceramic coating. Stainless offers corrosion resistance and longevity; ceramic coatings help retain heat inside the pipes, lowering under‑hood temperatures and improving exhaust velocity. Some designs include a catalytic converter in the primary pipe; others are full catless units intended strictly for off‑road or track use (check local emissions laws before purchasing). Popular BRZ header brands include Tomei, JDL, Gruppe‑S, and Invidia.

Whether you’re chasing peak power, sharper throttle response, or a better soundtrack, header installation is one of the highest‑value bolt‑on mods for the FA20 engine. However, a well‑executed install is critical to prevent leaks, check‑engine lights, and performance losses. This expanded guide walks you through everything from preparation to post‑install tuning.

Tools and Parts Needed

Having every tool and component on hand before you start avoids mid‑job trips to the parts store. Below is a comprehensive list; items marked with * are less common but highly recommended for a trouble‑free install.

Complete aftermarket header set (including all gaskets and hardware supplied by manufacturer)
3/8” and 1/2” drive socket set with extensions (10mm, 12mm, 14mm, 17mm, 19mm sockets)
Combination wrenches (12mm, 14mm, 17mm)
Torque wrench (capable of 30–80 lb‑ft)
Floor jack and two heavy‑duty jack stands
Safety glasses and mechanic’s gloves
Penetrating oil (e.g., PB Blaster or Kroil) *
Breaker bar (18” or longer) *
Oxygen sensor socket (22mm, slotted design) *
Anti‑seize compound (copper‑based for exhaust fasteners) *
New exhaust manifold gasket and copper nuts (OEM recommended for reuse if condition permits, but new is safer)
Heat‑resistant silicone sealant (high‑temp RTV) optional for added insurance at the collector joint
Shop rags and a catch pan for coolant if you disturb the crossover tube

Important: Some header kits include gaskets, but OEM Subaru gaskets tend to seal more reliably, especially on the cylinder head ports. Verify the gasket shape matches your engine’s cylinder head (2013–2020 BRZ/FA20).

Safety Precautions

Let the engine cool completely before starting. Exhaust components can reach temperatures higher than 800°F (425°C) and will cause severe burns if touched.

Work on a level, paved surface. Never rely on a jack alone; always use jack stands rated for the vehicle’s weight (the BRZ curb weight is ~2,760 lb).
Disconnect the negative battery terminal to prevent accidental shorting of sensors or the starter.
Use a fire extinguisher rated for Class B and C within reach — fuel and oil vapors are always present in an engine bay.
Wear gloves to protect against sharp edges and hot surfaces, plus safety glasses when working under the vehicle.

Step-by-Step Installation

Step 1: Prepare the Vehicle and Gain Access

Park the car, engage the parking brake, and chock the rear wheels. Disconnect the negative battery terminal. Jack up the front and place jack stands under the front pinch welds (use a rubber pad or wood block to protect the paint). Remove the driver‑side front wheel to improve access to the header bolts — this is not strictly required but saves time and frustration.

Step 2: Remove the Factory Exhaust Manifold

Start by spraying all exhaust manifold nuts and bolts with penetrating oil. Allow it to soak for at least 10 minutes. The stock manifold is secured to the cylinder head with eight 12mm nuts (two per port) and two additional nuts that attach the manifold to the front pipe/cat assembly.

Unplug the primary oxygen sensor located on the factory manifold using the slotted sensor socket. If the sensor is stubborn, apply heat with a small acetylene torch (or careful propane) to break the corrosion. Do not use an impact gun on the oxygen sensor — the threads are fine and easily damaged. Once unplugged, thread the sensor out and set it aside safely.

Using a 12mm socket and a breaker bar, loosen and remove the eight header‑to‑head nuts. The top rear nut on each side can be tight; a wobble extension helps. Remove the two studs that connect the manifold to the midpipe. The factory manifold will then drop out downward — you may need to rotate it slightly to clear the subframe. On some models, the rubber engine hanger bracket interferes; having a pry bar or long screwdriver to gently flex it out of the way is helpful.

Common challenge: The water pipe crossover underneath the intake manifold may block removal on early BRZ models. Loosen the two 10mm bolts holding the water pipe bracket to the block and shift it aside. You do not need to drain coolant if you are careful — the pipe remains sealed if you do not disturb the hose clamps.

Step 3: Prepare the New Header

Before installing the aftermarket header, check the gasket surfaces for flatness. Lay the supplied gasket or your new OEM gasket against the header flange. Any burrs or weld spatter can be removed with a fine file or sandpaper (200 grit). Apply a thin layer of anti‑seize to all stud threads and to the oxygen sensor threads (only on the sensor base, not the tip).

Step 4: Install the New Header

Raise the header into position from below. It helps to loosely install the two nuts that secure the header to the midpipe/overpipe first — do not tighten yet. Align the cylinder head ports and start the eight header nuts by hand. For headers with a divided collector (e.g., ELH designs), ensure no gasket blows out during tightening. Tighten the header‑to‑head nuts in a cross pattern using the torque wrench to the factory specification 30 lb‑ft (40 Nm).

Now tighten the midpipe connection. If your header kit came with a new donut gasket or two‑bolt flange gasket, use it. Torque the two studs to 35 lb‑ft (47 Nm). Reconnect the oxygen sensor — plug it into the harness first, then thread it into the bung hand‑tight, and finally torque to 25 lb‑ft (34 Nm).

Step 5: Final Checks and Lowering

Inspect all connections visually. Ensure nothing is touching the steering shaft, lower control arm, or oil pan. Some long‑tube headers may contact the steering rack; if so, loosen the header nuts and shift the header slightly, retightening. Reinstall the wheel, lower the vehicle, and reconnect the battery.

Post-Installation Checks and Break-In

Start the engine and listen: A ticking sound from the header area usually indicates an exhaust leak at the head flange. If the sound persists after warm‑up, retorque the header nuts with the engine hot (use a rag to protect your hands).
Check for leaks: With the engine idling, run your hand (carefully!) around the flange joints while wearing a glove. Better yet, listen with a stethoscope or a piece of hose. A visual smoke test is ideal but not essential.
Monitor the OBD‑II system: Drive the car gently for the first 20 miles. Header installs can trigger a catalyst efficiency code (P0420) if you have a catless or high‑flow cat header. A tune or an oxygen sensor spacer is needed to clear it — see the tuning section below.
Wait before hard driving: Give the header a heat‑cycle break‑in: drive normally for 50 miles, then do a few pulls to redline to seat the gaskets and allow expansion. Retorque the nuts after the first heat cycle (engine cold) to compensate for thermal settling.

Common Issues and Troubleshooting

Problem	Likely Cause	Solution
Exhaust leak (ticking) after installation	Nuts not fully torqued or gasket misaligned	Retorque all nuts in sequence; if leak persists, replace gasket with OEM
Check engine light on with P0420	Cat efficiency below threshold (catless or high‑flow cat)	Install an oxygen sensor spacer (angled or “mini‑cat”) or get a tune
Rattling sound from engine bay	Header contacting subframe or steering shaft	Inspect clearance; use a pry bar to indent the heat shield or loosen and reposition header
Exhaust smell in cabin	Leak at collector or midpipe joint	Inspect and replace gasket; apply high‑temp RTV if needed
Loss of low‑end torque	Exhaust scavenging mismatch (common with very long‑tube, large‑diameter headers)	Pair with a tune that adjusts VVT and fuel/timing maps for the header

Performance Tuning After Header Installation

Headers alone improve airflow, but the ECU will not fully exploit them without calibration changes. The BRZ’s engine uses a speed‑density system; after significant exhaust changes, the air‑fuel ratio may lean out at high rpm or cause a catalyst efficiency code. For maximum gains and drivability, consider the following options:

ECU reflash/tune: Companies like Open Flash Performance and ECUtek offer off‑the‑shelf tunes for headers. A remote tune with data logging can be done with a Tactrix cable. Expect 10–15 hp increase from the tune alone after headers are installed.
Oxygen sensor spacer: If you are not ready for a tune, a catalytic converter simulator (a metal spacer with a small chamber) often tricks the rear O2 sensor into staying below the threshold for P0420. Brands like “Big Daddy” or “Angled Mini‑Cat” work well on FA20 engines.
Cold air intake: Matching an intake with the header tune can pick up an additional 5–8 hp. Ensure the tune covers both modifications.
Check for boost leaks: If you have a supercharged or turbocharged BRZ, header swap changes backpressure and may require a boost controller retune. Consult a professional tuner.

Header Maintenance and Care

Stainless steel headers can discolor or even crack if stressed. To keep them in top condition:

Inspect header nuts and flange bolts every oil change for tightness — vibrations can loosen them over time, especially on lightweight iterations.
If you drive in winter or rainy conditions, wash salt off the undercarriage regularly. Even 304 stainless can form superficial “tea stains.”
Ceramic‑coated headers: Avoid using acidic wheel cleaners; wipe down with a mild soap and water after each track day.
Re‑torque after the first 500 miles and again after 2,000 miles. Metal expansion cycles eventually settle the gaskets.
If the header develops a crack (usually near the weld at the collector), remove and weld repair by a competent TIG welder. Do not continue driving — cracks can enlarge and cause debris ingestion into the turbo or engine.

Conclusion

Installing headers on your Subaru BRZ is one of the most rewarding upgrades you can perform in a weekend. It unlocks additional horsepower, sharpens throttle response, and gives your car a more authoritative exhaust note. By following the detailed preparation, removal, and torque procedures outlined here — and planning for a tune — you can avoid common pitfalls like leaks, CELs, and rattles. Remember that safety comes first: a properly supported car and a cool engine are non‑negotiable. With patience and the right tools, your BRZ will breathe easier and reward you with a more exhilarating driving experience.

For further reading, check the Subaru BRZ owner forums at FT86Club or refer to the manufacturer’s instructions that come with your header kit. Always cross‑reference bolt torque values with a factory service manual if available.