Why Install Takeda Headers on Your GR86

The GR86’s FA24 engine is a strong performer from the factory, but the stock exhaust manifold—a cast-iron log-style piece with restrictive catalytic converters—leaves significant power and sound on the table. Swapping in a set of Takeda headers unlocks a more aggressive exhaust note, improves throttle response, and can add measurable horsepower and torque. This guide covers everything you need for a successful installation, from tool selection and safety precautions to sound and performance expectations after the swap.

Takeda offers both catted and uncatted versions of their headers for the GR86. The catted option retains a high-flow catalytic converter, making it street-legal in most states (check local laws) while still freeing up flow. The uncatted race version delivers maximum gains but is intended for off-road or track use only and will trigger a check engine light without a tune. Both designs feature mandrel-bent 304 stainless steel tubing and CNC-machined flanges for a leak-free seal.

Tools and Supplies You’ll Need

Before starting, gather everything in one place. Rushing to find a missing tool mid-job can lead to mistakes. Here’s a complete list:

  • Takeda headers (specific to the GR86, part number varies by catted/uncatted version)
  • Ratchet set with extensions and a universal joint (10mm, 12mm, 14mm, 17mm sockets)
  • Torque wrench capable of readings in ft-lb and in-lb
  • Jack and two jack stands (a low-profile jack is helpful)
  • Safety glasses and mechanic’s gloves
  • New exhaust gaskets (header-to-engine and header-to-front pipe) – Takeda often includes them, but having spares is wise
  • Copper anti-seize compound for bolts and O2 sensor threads
  • Thread locker (medium strength, e.g., Loctite 243) for exhaust bolts
  • O2 sensor socket (22mm) – trust us, a regular wrench rarely works on the rear sensor
  • Breaker bar for stubborn manifold bolts
  • Penetrating oil (WD-40 Specialist, PB Blaster, or Kroil) – soak bolts the night before
  • Shop rags and a vacuum/debris blower to keep work area clean
  • Engine coolant (if you remove the intake manifold support bracket – likely not needed, but have a small amount just in case)

Preparation and Safety

Park the GR86 on a level concrete surface. Allow the exhaust and engine to cool completely—burn risk is real. Disconnect the negative battery terminal and isolate it (wrap the cable end in a rag or use a terminal cover). This prevents any electrical shorts and resets the ECU, which helps the engine re-learn fuel trims after the header swap.

Place wheel chocks behind the rear wheels. Lift the front of the car using the central front jack point, then set jack stands under the factory pinch-weld points (front lift points). Lower the car onto the stands so they bear the weight. Give the chassis a firm shake to confirm stability before sliding underneath.

To make the job easier, consider removing the driver-side front wheel. This opens up access to the lower heat shield bolts and makes it simpler to reach the O2 sensor connector behind the fender liner. If you have flexible socket extensions, you can work around the wheel, but removing it reduces frustration.

Step-by-Step Header Installation

Step 1: Remove the Under-Engine Covers and Heat Shields

Begin by removing the plastic undertray (a 10mm socket and a few push-clips). Next, locate the metal exhaust heat shields covering the stock manifold. Usually there are two: one upper shield that bolts to the block, and one lower shield that sits under the manifold. All use 10mm or 12mm bolts. Soak them with penetrating oil and remove carefully—rust is common on these fasteners even on relatively new cars.

Step 2: Unplug the O2 Sensors

The stock header has two oxygen sensors: a front (upstream) sensor screwed into the manifold itself, and a rear (downstream) sensor in the front pipe just behind the manifold flange. Reach behind the passenger-side engine bay to disconnect the upstream sensor harness connector. For the downstream sensor, unclip the harness from a bracket on the transmission bellhousing. Use the O2 sensor socket to loosen both sensors from their bungs. Do not force the sensors—apply penetrating oil and gentle back-and-forth motion. Once loose, unscrew them completely and set aside where they won’t be damaged.

Step 3: Remove the Stock Exhaust Manifold

Working from underneath, unbolt the stock manifold from the engine block. There are 8 nuts (12mm) securing it to the cylinder head. A long extension with a universal joint works best for the upper ones. Once all nuts are off, rock the manifold gently to break the gasket seal—it will be stuck from heat cycles. Lower the manifold carefully, taking care not to damage the studs. You may need to rotate it to clear the front subframe.

If the manifold is stubborn, a few raps with a rubber mallet can help, but never hit the block or studs directly. Clean the gasket mating surfaces on the cylinder head with a plastic scraper and brake cleaner. Ensure no old gasket material falls into the exhaust ports.

Step 4: Transfer the O2 Sensors to the Takeda Header

Before installing the new header, install the O2 sensors into the Takeda bungs. Apply a small amount of anti-seize to the sensor threads (not the tip). Torque them to 30 ft-lb (or per sensor manufacturer spec). Ensure the downstream sensor wiring won’t contact the header tubes—route it through the same paths as the stock harness.

Step 5: Install the Takeda Header

Position the header gasket (included or purchased separately) onto the cylinder head studs. The gasket is usually a multi-layer steel (MLS) type—it has a specific orientation; the raised side faces the head. Lift the Takeda header into place and thread the 8 nuts by hand. Tighten them gradually in a crisscross pattern to avoid warping the flange. Torque: follow Takeda’s spec (typically 25–30 ft-lb for the head nuts).

At the collector flange (where the header meets the front pipe), install the supplied triangular gasket and hand-start the two bolts (14mm). Torque to 40–45 ft-lb. Do not overtighten—this is a common source of flange cracking on thin-wall headers.

Step 6: Reinstall Heat Shields, Covers, and Wheels

Refit the upper heat shield over the new header if it clears (some aftermarket headers require you to leave it off or trim it). Reinstall the lower heat shield and under-engine tray. Reconnect the O2 sensor harnesses and secure with zip ties if needed to prevent contact with moving parts. If you removed the driver-side wheel, put it back on and torque the lug nuts to 80 ft-lb.

Step 7: Reconnect Battery and Check for Clearance

Reconnect the negative battery terminal. Start the engine and let it idle. Walk around the car and listen for any exhaust leaks—a ticking or hissing sound indicates a poor seal at the flanges or head. Use a shop towel to check for sooty leaks at each joint. If you find one, tighten the bolts slightly (no more than 5 ft-lb beyond spec) or inspect gasket alignment.

Check clearance between the header and the steering shaft, subframe, and sway bar. Takeda headers are designed to fit without interference, but verify there’s at least a finger’s width of space. If you hear a rattle under load, something is touching—reposition the header or add heat shield wrap where needed.

Step 8: First Drive and ECU Relearn

Take the car on a gentle 15-20 minute drive, varying engine RPM. This lets the ECU begin its relearn process. Avoid full throttle until the engine reaches operating temperature. After the drive, park and let the car cool, then re-torque the header nuts once more (the gaskets compress slightly).

Sound Expectations With Takeda Headers

The exhaust note of a GR86 with Takeda headers is dramatically different from stock. Here’s a breakdown of what you can expect:

Cold Start and Idle

On a cold start, the engine will produce a louder, guttural bark that may surprise neighbors. This lasts about 30 seconds before settling into a deeper idle with a noticeable low-frequency rumble. With the catted version, the idle is about 40% louder than stock; with catless, the idle gains a raw, racier edge.

Low-Speed Cruising

Driving at low RPM (under 3000) reveals more bass and drone than stock, but it remains civil inside the cabin. The Takeda design uses internal baffling to minimize annoying resonance. Highway cruising at 70 mph produces a mild hum—not enough to make conversation difficult.

Full Throttle and High RPM

From 4000 RPM to redline, the sound transforms into a sharp, aggressive scream. The boxer engine’s signature rumble becomes more pronounced, with a metallic howl that is especially satisfying on upshifts. The catted version maintains a crisp note; the catless version adds a slightly raspy top-end that some love and others find a bit raw.

Comparison to Other Header Brands

Compared to the torque-smoothing design of Borla or the long-tube JDL headers, Takeda strikes a balance between volume and tone. It is louder than Gruppe-S UEL headers but less booming than the Tomei equal-length offering. If paired with a full catback exhaust (e.g., the Takeda catback), expect a track-ready volume that demands earplugs for extended drives.

Performance Gains and Tuning Considerations

Untuned Gains

Even without a custom tune, Takeda headers will improve throttle response and provide a seat-of-the-pants increase in mid-range pull. Most owners report a gain of 5–8 whp in the 3500–6000 RPM band. The ECU will adapt fuel trims to some extent, but the stock calibration cannot fully compensate for the increased flow, especially near the top end.

Why You Need a Tune

For maximum power and reliability, a proper ECU tune (via EcuTek, COBB Accessport, or OpenFlash) is strongly recommended. With a tune, the 2.4L boxer can see 15–20 whp gains, plus a flatter torque curve. More importantly, tuning eliminates the risk of running lean at high RPM, which can cause pre-detonation and valve damage over time. The tune also turns off the check engine light that often appears with catless headers due to the rear O2 sensor reading.

If you plan to keep the stock front pipe and catback, the gains are still worthwhile. However, upgrading to a high-flow front pipe and catback exhaust will amplify both power and sound.

In many regions, removing the primary catalytic converter (catless header) is illegal for street use and will fail emission inspections. Takeda’s catted header retains a high-flow metallic substrate converter that, when paired with the stock exhaust, should pass a sniffer test in most areas. Check local laws before purchasing. Some states, like California, require a CARB Executive Order number—Takeda catted headers are not CARB-legal, so be aware if you live in a strict emissions state.

Running without a tune and with catless headers will trigger a P0420 code (catalyst efficiency below threshold). A tune can eliminate the code, but that does not make the car emissions-legal in jurisdictions that require visual inspection.

Common Pitfalls and Pro Tips

  • Broken studs: The factory manifold nuts can be seized. If a stud breaks in the cylinder head, you’ll need a stud extractor—a miserable job. Always soak with penetrating oil and use a six-point socket on nuts.
  • O2 sensor wire routing: The downstream sensor on the Takeda header sits further back than stock. Extend the wire harness using a soldered extension or buy an O2 sensor harness extension kit. Do not simply stretch the wires—they will pull loose.
  • Heat management: The header tubes run close to the alternator and starter. Consider wrapping the header with titanium exhaust wrap or applying a ceramic coating to reduce underhood temperatures. Heat wrap also protects the rest of the engine bay from radiant heat.
  • Re-torque after first heat cycle: Stainless steel expands more than cast iron. Recheck all bolts after 100–200 miles. Loose bolts cause leaks and rattles.
  • Don’t skip the gasket inspection: Even if Takeda provides gaskets, buy a high-quality OEM or Grimmspeed gasket set for the head ports—they often seal better on the FA24.

Final Verdict

Installing Takeda headers on your GR86 is one of the most rewarding bolt-on modifications you can do. The sound alone transforms the car from a polite daily driver into an enthusiast machine with a voice that matches its handling. When paired with a tune, the performance gains are substantial and well worth the cost. Follow the steps above, take your time, and you’ll be rewarded with a setup that brings the FA24 engine to life.

For additional resources, check the official Takeda product page for torque specs and warranty details, the FT86 SpeedFactory header installation thread for community tips, and EcuTek’s tuning guide for learning about GR86 ECU adjustments.