Why Upgrade Your A90 Supra Downpipe?

The A90 Toyota Supra’s factory downpipe is a compromise between performance, emissions, and noise regulations. Replacing it with a genuine Toyota performance downpipe unlocks significant gains in horsepower and torque, especially in the mid-range, while improving exhaust flow and turbo spool response. Using genuine Toyota parts ensures perfect fitment, factory-level sealing, and compatibility with the vehicle’s sensors and emissions systems. This guide provides a detailed, step-by-step approach for a safe and effective install.

Performance & Sound Benefits

A high-flow downpipe reduces backpressure, allowing the twin-scroll turbocharger to breathe more freely. Expect gains of 15–25 hp and a deeper, more aggressive exhaust note without excessive drone. The genuine Toyota downpipe maintains the integrated catalyst substrate for responsible emissions compliance while delivering these improvements.

Tools and Materials Needed

Essential Tools

  • Socket set – 10mm, 12mm, 14mm, 17mm sockets for various fasteners
  • Torque wrench – 3/8” or 1/2” drive, range 10–60 ft-lb for precise tightening
  • Ratchet – long-handle for leverage
  • Extension bars – 3” and 10” to reach tight bolts
  • Jack and jack stands – 3-ton capacity, always use four stands for stability
  • Penetrating oil – WD-40 or CRC Freeze-Off for rusted bolts
  • Shop towels/rags – for cleaning and wiping residual oil
  • Safety goggles and gloves – protect against debris and sharp edges

Parts Required

  • Genuine Toyota A90 Supra downpipe – available through Toyota Parts Direct or your local dealer
  • New gaskets – turbo-to-downpipe and downpipe-to-midpipe (reuse not recommended)
  • Replacement hardware – bolts, nuts, springs if included in kit
  • Anti-seize compound – optional but helpful for future removal

Preparation Steps

Workspace and Vehicle Setup

Choose a well-ventilated area with concrete floor. Park on level ground, engage the parking brake, and chock the rear wheels. Disconnect the battery negative terminal to prevent any electrical short or accidental starter engagement. Allow the exhaust system to cool completely – at least one hour after driving.

Lifting the Vehicle Safely

Use a floor jack at the front subframe crossmember, then place jack stands under the front jack points (just behind the front wheels). Lower the car onto the stands and ensure it’s firmly supported. Do not rely solely on the hydraulic jack. For extra clearance, you may also lift the rear slightly.

Remove Underbody Panels

The factory undertray may block access. Using a 10mm socket, remove the fasteners along the front section. Set them aside in order. You may also need to remove a heat shield attached to the transmission tunnel for better access to the downpipe bolts.

Removing the Stock Downpipe

Step 1: Access and Lubricate Bolts

Locate the stock downpipe between the turbocharger outlet and the midpipe. Spray penetrating oil on all four bolts connecting the downpipe to the turbo (14mm) and the two bolts at the midpipe flange (12mm). Allow 5–10 minutes for the oil to penetrate threaded joints.

Step 2: Disconnect Sensors

Unplug the oxygen sensors (both upstream and downstream if present). Compress the locking tab and pull the connectors apart. Use a pick tool to release the sensor wire clips from the downpipe bracket. Mark the sensor locations to avoid mixing them after installation.

Step 3: Remove Bolts

Using a 14mm socket and extension, loosen the four turbo-to-downpipe bolts. Work in a cross pattern to prevent warping the flange. Remove them completely and set aside. Next, remove the two bolts at the midpipe flange. If the flange is stuck, gently tap with a rubber mallet to free it.

Step 4: Remove the Downpipe

Slide the downpipe rearward and downward. It may require tilting to clear the subframe. Take care not to damage the transmission housing or turbo oil lines. If stuck, re-spray penetrating oil around the flange and tap the pipe body. Once free, extract it from under the car.

Preparing the New Downpipe Installation

Inspect the Turbo and Midpipe Flanges

Clean the turbo outlet flange and midpipe flange with a shop towel to remove carbon deposits and old gasket material. Use a small wire brush if needed. The mating surfaces must be smooth for a proper seal.

Install New Gaskets

Place the new gasket on the turbo flange (the triangular metal gasket). Ensure it seats evenly. Apply a thin layer of anti-seize to the threads of the new bolts to prevent galling. For the midpipe connection, use the provided gasket or a standard doughnut gasket; place it over the studs.

Installing the New Genuine Toyota Downpipe

Step 1: Position the Downpipe

With the help of an assistant, position the new downpipe from underneath the vehicle. Align the turbo flange with the turbo outlet and the midpipe flange simultaneously. It helps to start the downpipe at an angle and rotate it into place. Do not force it – genuine Toyota parts fit precisely.

Step 2: Secure the Turbo Flange

Thread the four 14mm bolts hand-tight. Use a cross pattern to ensure even pressure. Then torque to 28 ft-lb (38 N·m) using a torque wrench. Follow the factory specification exactly – overtightening can distort the flange.

Step 3: Attach the Midpipe Flange

Install the two 12mm bolts at the midpipe flange. Hand-tighten, then torque to 32 ft-lb (43 N·m). Recheck both sets of bolts after a few minutes.

Step 4: Reconnect Sensors

Plug the oxygen sensors back into their respective connectors. Route the wires away from hot surfaces and secure with the original clips. Ensure the locking tabs click fully. If your Supra has a second downstream sensor (for emissions monitoring), mount it into the bung on the new downpipe.

Final Steps After Installation

Reinstall Underbody Panels and Heat Shields

Replace any removed undertray fasteners and heat shields. Torque to 8 ft-lb – do not overtighten plastic fasteners. Ensure all clips are secure.

Reconnect the Battery

Attach the negative terminal and tighten the nut. Start the engine and let it idle for 3–5 minutes. Listen for exhaust leaks at both flanges – a failing gasket will produce a ticking sound that increases with revs. If you suspect a leak, shut off the engine and retorque the bolts.

Check for Check Engine Light

The genuine Toyota downpipe includes a catalytic converter, so the check engine light should not illuminate. However, if you experience a P0420 code (catalyst efficiency below threshold), it may indicate a pre-existing issue or a need to drive the car through a full warm-up cycle to allow the ECU to adapt. For maximum performance, consider a professional ECU tune – contact a reputable Supra tuner for recommendations.

Test Drive Protocol

Lower the car completely. Take a short drive (5–10 miles) with varying loads – avoid full throttle initially. Return to a safe location and recheck all bolts for tightness after the thermal cycles. Listen for any abnormal noises.

Maintenance and Longevity Tips

  • Inspect the downpipe bolts at every oil change – reapply anti-seize if removed.
  • Use genuine Toyota gaskets only; aftermarket gaskets may not withstand temperature cycles.
  • If the car is used for track days, consider wrapping the downpipe with exhaust wrap to reduce underhood temperatures.
  • Avoid aggressive engine braking until the downpipe is fully heat-cycled (about 500 miles).

A Note on Tuning and Emissions

While the genuine Toyota downpipe is designed to pass smog checks, pairing it with an aftermarket tune may affect emissions compliance. Always consult local regulations before modifying. The downpipe alone does not require a tune, but to fully realize the power gains, a custom calibration is recommended. Use reputable tuning software such as Bootmod3 or MHD Flasher if you choose to remap.

Conclusion

Installing a genuine Toyota downpipe on your A90 Supra is a rewarding upgrade that improves both performance and driving excitement. By following this detailed guide and using factory-quality parts, you ensure reliable fitment and lasting durability. Always prioritize safety, use the proper torque specifications, and don’t hesitate to consult a professional mechanic if you encounter unexpected steps. With careful installation, your Supra will deliver a more responsive and thrilling driving experience.