Tools and Materials Needed

Before beginning, gather the following tools and supplies. Having everything on hand minimizes interruptions and ensures you work safely.

  • FA24 Performance Exhaust kit (cat‑back or axle‑back, depending on your purchase)
  • Socket set (metric, 10‑19 mm, with extensions and a universal joint)
  • Combination wrench set (metric, 10‑19 mm)
  • Torque wrench (rated for 10‑80 ft‑lb)
  • Floor jack and two jack stands (3‑ton capacity minimum)
  • Safety glasses and mechanic’s gloves
  • Penetrating oil (e.g., WD‑40 Specialist, PB Blaster)
  • Anti‑seize compound (copper or nickel based)
  • Trim removal tool (for plastic hanger retainers, if equipped)
  • Shop rags and a drain pan (in case of accidental fluid drip)
  • Digital camera or phone (take reference photos of the stock system before removal)

Many FA24 exhaust kits include new gaskets, bolts, and hanger rubbers. Verify all parts are present by comparing against the kit’s inventory list before you lift the vehicle.

Pre‑Installation Preparation

Park the car on a level, hard surface. Allow the engine to cool completely – hot exhaust components can cause severe burns. Disconnect the negative battery terminal (12 mm socket) to prevent accidental electrical shorts and clear any diagnostic trouble codes that might appear during the swap. If your vehicle uses electronic exhaust valves, you may need to disconnect the valve actuator harness; consult the kit instructions.

Check the ground clearance under the rear of the car. For most FA‑powered platforms (Subaru WRX, BRZ, etc.) the stock exhaust hangs low enough that you can work without lifting if you’re comfortable. However, using a jack and stands provides better access to the hangers and flange bolts. Always place stands under the designated lift points – consult your owner’s manual for exact locations.

Understanding the FA24 Exhaust System

The FA24 engine (2.4‑liter, turbocharged in most applications) is designed to flow efficiently but the stock exhaust often introduces restrictive bends, narrow pipe diameters, and muffling chambers that choke high‑RPM power. A performance exhaust such as the FA24 Performance Exhaust replaces these restrictive sections with mandrel‑bent tubing, larger diameter (e.g., 2.5” or 3”), and lower‑restriction mufflers.

Dyno testing on a stock FA24 WRX shows peak gains of up to 15 horsepower and 12 lb‑ft of torque at the wheels, with the largest improvements occurring between 3500–5500 RPM. The results depend on the specific kit, fuel quality, and ambient conditions. For maximum benefit, many tuners pair the exhaust with a custom ECU recalibration. Even without a tune, the exhaust reduces backpressure, improves throttle response, and delivers a sportier sound.

Step‑by‑Step Installation

1. Lift and Secure the Vehicle

Position the jack under the rear differential or the prescribed cross‑member lift point. Raise the vehicle until the rear wheels are about 2 inches off the ground. Place jack stands under the rear jacking points and lower the vehicle onto the stands. Give the car a firm shake at the bumper to confirm stability.

2. Remove the Stock Exhaust

Spray all flange bolts and hanger rubbers with penetrating oil and wait 10 minutes. Working from the back forward:

  • Disconnect the exhaust valve actuator wiring (if equipped) by pressing the tab and pulling the connector apart. Set the actuator aside where it won’t dangle.
  • Remove the rear section hangers by pulling the rubber isolators off the metal posts. Use a trim tool to pry stubborn ones.
  • Unbolt the flange connecting the rear section to the mid‑pipe (14 mm or 17 mm bolts).
  • Support the rear section with your free hand or a transmission jack, then slide it out from under the car.
  • Repeat for the mid‑pipe: remove hangers, unbolt the flange at the catalytic converter or downpipe, and remove the pipe.

If bolts are rusted and refuse to turn, apply additional penetrating oil and use a breaker bar. Do not force them – soaking overnight may be necessary for vehicles in the rust belt.

3. Prepare the New Exhaust

Lay the new FA24 Performance Exhaust parts on a clean tarp. Compare each pipe’s shape and hanger location to the stock parts. Apply a thin coat of anti‑seize to the threads of all supplied bolts and the inner surfaces of the slip‑joint connectors (if applicable). Lightly lubricate the new hanger rubbers with soapy water to ease installation.

4. Install the New Cat‑Back or Axle‑Back

Starting at the front (catalytic converter or downpipe flange):

  • Place the mid‑pipe section in position and hand‑tighten the two flange bolts using a new gasket (if supplied). Do not fully tighten yet.
  • Install the hanger rubbers onto the corresponding posts on the underbody. You may need to push firmly – a little soapy water helps.
  • Attach the rear muffler section to the mid‑pipe flange, again hand‑tightening with a new gasket.
  • Engage the rear hanger rubbers and the exhaust valve actuator (if your kit retains the electronic valve). Plug in the actuator harness.

Align all pipes so that they are centered in the bumper cutout and have at least 1 inch of clearance to the rear differential, sway bar, and chassis. Snug the bolts with a torque wrench to the manufacturer’s specification – typically 30–45 ft‑lb for flange bolts. Work from front to back to avoid binding.

5. Final Tightening and Torque Check

With every hanger engaged and the exhaust hanging freely, perform a final torque pass on all flanges. Check that the exhaust tips sit evenly in the bumper cutouts – long oval or quad‑tip designs often require slight adjustment by loosening clamps, repositioning, and retightening. Use a torque wrench to ensure you do not over‑torque and strip threads.

6. Leak Test and Sound Check

Before lowering the car, start the engine and let it idle. Feel around the flanges with your gloved hand (careful: the pipes will be hot after a minute) for escaping exhaust gas. A small amount of smoke or a strong smell indicates a leak. Listen for hissing or ticking that disappears when you press a rag over the joint. If a leak is present, tighten the bolts slightly while the engine is off and cool. Re‑check.

Allow the engine to reach operating temperature. The new exhaust will produce a louder, more aggressive tone at idle and under load. This is normal. If you hear rattling or metallic contact with the chassis, adjust the hangers or pipe alignment before proceeding.

7. Lower the Vehicle

Turn off the engine. Remove the jack stands and lower the car to the ground. Reconnect the battery terminal. Start the engine again and let it run for two minutes to re‑learn idle settings. Check that all exhaust tips are still positioned correctly.

Post‑Installation Break‑In and Tips

Drive the car gently for the first 50 miles to allow the gaskets to seat and the exhaust system to settle. After this break‑in period, perform a re‑torque of all flange bolts – they can loosen as the gaskets compress. Many kits recommend checking torque again after the first heat cycle.

Expect the sound to become slightly louder and deeper after a few hundred miles as carbon builds up inside the mufflers. If the exhaust is overwhelmingly droning, consider adding a resonated mid‑pipe or leaving the stock muffler resonator in place (if you installed an axle‑back only).

Monitor the check engine light for the first week. While a cat‑back swap rarely triggers a code, some vehicles may report a “catalyst efficiency” code if you removed a secondary catalytic converter (this should only happen with a downpipe‑back system). If a light appears, read the code with an OBD‑II scanner and consult your tuner.

Performance Expectations and Tuning Considerations

The 15‑horsepower gain quoted for the FA24 Performance Exhaust is achievable on a stock‑tuned engine when tested on a heartbreaker dyno. Real‑world gains are often between 10–15 wheel horsepower with a solid torque increase across the mid‑range. To unlock the full potential, many owners pair this exhaust with an accessport or ECU reflash. A simple Stage 1 tune (no other modifications) can raise the total gain to 20–25 wheel horsepower.

Note that the sound level will increase, possibly enough to exceed noise limits at some tracks. If you plan to track the car, check with your local organization for decibel restrictions. For daily driving, the exhaust is well‑muffled and produces no drone at highway cruising.

For more information on performance exhaust theory and installation best practices, refer to these resources:

Final Thoughts

Installing the FA24 Performance Exhaust is one of the most rewarding bolt‑on modifications you can make. The process is straightforward and can be completed in a weekend with basic hand tools. The payoff – a cleaner exhaust note, sharper throttle response, and a genuine 15‑horsepower increase – makes every step worthwhile. Always follow the kit‑specific instructions and torque values, and don’t be afraid to ask for a second pair of hands when aligning the rear section. With careful work, your FA24 will sound as powerful as it truly is.