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RX-8 Cat-back exhaust

Your RX-8

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+0–3 whp (est.)
Medium$400–$1,0001–1.5 hrs
All RX-8 mods

Why do it

Mostly a sound upgrade on a stock RX-8. Expect little to no power gain on its own.

Tools you'll need

Parts to buy

Always double-check fitment for your exact year, trim and transmission before buying. Prices change. ModBuddy doesn't earn money from these links.

Official guides & videos

Before you start

  • The exhaust must be completely cold.
  • If your car doesn't have the Mazdaspeed rear bumper lip, some exhausts need the plastic tailpipe surrounds trimmed. Check your kit.

Video guide

Invidia cat-back exhaust install on an RX-8
by Driven By Madness on YouTube

Different exhaust brand, same removal and hanger steps. Skip the heat-shield repair (3:08–5:10); that was only for his rusty car. Each ▶ button below jumps to that step in the video.

Watch the whole video

Steps

  1. Raise the car

    • Support the car securely on jack stands with enough room to slide the exhaust out the back.
    Watch this step (0:52–1:08)

  2. Unbolt at the cat pipe

    • Remove the two 17mm nuts and their springs where the exhaust meets the catalytic converter pipe. Keep them. Many kits reuse them.
    Watch this step (1:08–1:39)

  3. Slide off the hangers

    • Spray the five rubber hangers with WD-40 and pry the exhaust's hooks out of them.
    • Lower the old exhaust with a helper. It's long and awkward.
    Watch this step (1:39–2:58)

  4. Hang the front section

    • Fit the new front pipe to the cat pipe flange and into its hanger.
    • Start the original nuts and springs but don't tighten them yet. Squeezing the springs with channel-locks helps the nuts start.
    Watch this step (5:10–6:00)

  5. Hang the muffler section

    • Fit the muffler into the rear hangers and join it to the front section with the supplied bolts, washers and gasket.
    • Make sure the flanges are square, then tighten that joint.
    Watch this step (5:10–6:00)

  6. Tighten the front joint

    • Tighten the front spring nuts until there's about 1mm left between the spring coils. Don't overtighten.
    Watch this step (6:00–6:31)

  7. Trim the surrounds (if needed)

    • If the tips sit too close to the bumper surrounds, remove the surrounds (they're held by clips and push pins), trim them carefully and reinstall.
    • Aim for at least 1/2" of clearance between the pipe and the plastic.

  8. Test

    • Lower the car, start it and check for leaks.
    • After a short drive, check that the exhaust isn't touching the bumper or surrounds.
    Watch this step (7:06–7:45)

How to know it worked

Safety first

  • Park on flat, solid ground, set the parking brake and chock the wheels.
  • Use jack stands rated for your car. Never get under a car held up only by a jack.
  • Let the engine and exhaust cool completely before touching them.
  • Disconnect the negative battery terminal before unplugging sensors or electrical parts.
  • Wear safety glasses, and gloves around sharp heat shields and hot fluids.
  • Tighten bolts to the torque spec in your factory service manual.
  • If a step doesn't match your car or you're unsure, stop and ask a shop.

These are overview steps written to help you plan the job. Always follow the instructions that come with your part and the procedures and torque specs in your factory service manual. Horsepower is an estimate; results vary.