Why Upgrade to a Greddy Exhaust System on Your Lexus IS?

Your Lexus IS is already a finely engineered machine, but the stock exhaust system is designed to balance noise regulations, cost, and comfort — not peak performance or an exciting note. Swapping to a Greddy exhaust system unlocks a deeper, more aggressive tone and can free up restricted airflow, leading to modest horsepower and torque gains. This guide walks you through the complete installation process, from removing the factory exhaust to enjoying the new sound profile. We’ll also cover tools, safety, and what to expect after the job is done.

Greddy is a trusted name in aftermarket performance parts, and their exhausts for the Lexus IS (models IS250, IS300, IS350, and IS F) are designed for a direct bolt-fit. Whether you’re a seasoned DIYer or a first-timer, you can complete this install in a weekend with the right preparation. Let’s get started.

For more background on Greddy exhausts, check the official Greddy website or browse community forums like Club Lexus for owner experiences.

Tools & Materials You’ll Need

Having everything ready before you lift the car saves time and frustration. Here’s a complete list:

  • Greddy exhaust system – confirm it matches your Lexus IS model and year
  • Socket wrench set – metric sizes (10mm, 12mm, 14mm, 17mm common)
  • Jack and jack stands or a quality lift – never work under a car supported only by a jack
  • Torque wrench – to tighten bolts to factory specs
  • Penetrating oil (e.g., WD-40 or PB Blaster) – helps loosen rusted bolts
  • Cutting tool (angle grinder or reciprocating saw) – sometimes needed if the old exhaust is seized
  • Rubber mallet – for persuading stubborn hangers
  • Safety goggles and gloves – non-negotiable
  • Rags, degreaser, and wire brush (optional but helpful for cleaning mating surfaces)
  • Exhaust gaskets – many Greddy kits include new ones, but have a spare set handy
  • Anti-seize compound – for threads to prevent future corrosion

Preparation Steps

1. Safety First

Park the Lexus on a flat, hard surface. Apply the parking brake and place wheel chocks behind the rear tires. Wear gloves and safety glasses. If the car has been running, let the exhaust pipes cool completely – they can cause severe burns.

2. Disconnect the Battery

Locate the negative terminal and disconnect the cable. This prevents any accidental contact with the starter or other electronics while you’re working near the drivetrain.

3. Lift the Vehicle

Using a jack, raise the rear of the car until you have enough clearance to work comfortably under the exhaust. Place jack stands under the factory lift points (consult your owner’s manual). Give the car a gentle shake to confirm it’s stable. Never rely solely on a hydraulic jack.

4. Inspect the Underbody

While you’re under there, check for rust, damaged heat shields, or leaking exhaust gaskets. Address any issues before proceeding. Use a wire brush and degreaser to clean the flange areas where the new exhaust will mate.

Removing the Stock Exhaust System

Step 1: Locate and Spray Bolts

Spray penetrating oil onto all nuts and bolts connecting the exhaust flanges – especially the ones at the catalytic converter and the hanger brackets. Let it soak for 5–10 minutes.

Step 2: Remove the Rear Section (Axle-Back or Cat-Back)

Most Lexus IS models have a two- or three-piece exhaust. Start at the rear: locate the bolts (usually 12mm or 14mm) that attach the muffler section to the mid-pipe. Remove them with a socket wrench. If they’re stubborn, a breaker bar or impact gun helps. Next, use the rubber mallet to gently tap the exhaust hangers out of their rubber mounts. Slide the rear section out from under the car.

Step 3: Remove the Mid-Pipe (If Applicable)

On many IS setups, the mid-pipe connects from the catalytic converter back to the rear section. Undo the flange bolts at the converter side. Again, spray penetrating oil if needed. Remove the hanger mounts and slide the mid-pipe out. Be careful – the old system might be heavy and can drop suddenly.

Step 4: Deal with Seized Hardware

If a bolt snaps or a nut rounds off, you may need to cut the old pipe. Use an angle grinder with a cutting wheel or a reciprocating saw. Cut as close to the flange as possible, then remove the remaining bolt with a bolt extractor or torch. It’s a good idea to have a replacement hardware kit on hand. Tip: Many Lexus forums recommend upgrading to stainless steel hardware during the install.

Step 5: Clean the Flanges

With the old exhaust off, clean the flanges on the catalytic converter and any intermediate pipes. Use a wire brush or sandpaper to remove corrosion and old gasket material. A clean surface ensures a proper seal and prevents exhaust leaks.

Installing the Greddy Exhaust System

Step 1: Test Fit the Components

Before tightening anything, loosely assemble the Greddy exhaust on the floor. Confirm all pipes and hangers are present. Place the new gaskets between each flange. Slide the entire system under the car in rough position.

Step 2: Mount from the Front to the Rear

Start at the catalytic converter flange. Attach the first section (downpipe or front pipe) using the supplied bolts and nuts. Do not fully tighten yet. Work your way back, connecting mid-pipes and then the rear section. Ensure each section is seated fully in its hanger mounts. Use the rubber mallet to push the hangers home if they’re snug.

Step 3: Align the Tips

Greddy systems typically come with adjustable exhaust tips. Before final tightening, adjust the tips so they are centered in the rear bumper cutouts. Check clearance to the bumper and heat shield. The tips should not touch the bumper when the car is at rest or under engine movement.

Step 4: Tighten Everything to Spec

Once alignment is perfect, use a torque wrench to tighten all bolts to the manufacturer’s specifications. Typically, flange bolts are torqued to 30–40 ft-lb. Check the Greddy manual for exact values. Torque in a criss-cross pattern to ensure even clamping. After tightening, wiggle each joint to confirm it’s secure.

Step 5: Recheck Hangers

Exhaust hangers should allow the system to move slightly but not droop. If a hanger is too loose, use a zip tie or aftermarket hanger stiffener. If it’s too tight, the system may transmit vibrations to the chassis. Most Greddy kits use OE-style rubber mounts.

Step 6: Anti-Seize & Reconnect Battery

Apply a small amount of anti-seize compound to exposed threads (avoid getting it on gaskets). This will make future removal much easier. Reconnect the battery negative terminal.

Post-Installation Checks

  • Visual inspection: Walk around the car and look for any exhaust contact with the underbody, suspension, or driveshaft.
  • Leak test: Start the engine and let it idle. Listen for hissing sounds near flange joints. If you suspect a leak, use a soapy water spray – bubbles will indicate escaping exhaust gas.
  • Torque re-check: After the first heat cycle (engine warm then cool), re-torque all bolts. Metal expands and contracts, so joints may settle.
  • Check for drone or rattles: Take a short test drive, varying speed and load. If you hear rattling, realign the tips or add heat shield material where clearance is tight.

Sound Test & Performance Observations

Now for the fun part – experiencing the new exhaust note. Start the engine from cold. Expect a deeper idle than stock, with a slight rumble on cold start. Let the engine reach operating temperature, then do the following:

  • Idle check: The note should be smooth, not overly loud. Some Greddy systems have a moderate drone at certain RPMs – that’s normal for a performance exhaust, but excessive drone may indicate an installation issue.
  • Light revs (2,000–3,000 RPM): You’ll hear a clean, sporty tone. The Lexus V6 or V8 will now have more personality.
  • Full throttle (4,000–6,500 RPM): Expect an aggressive scream or roar, depending on your engine. The IS350 with a Greddy system can sound truly menacing.
  • Highway cruising: At steady speed (60–75 mph), see if the drone is tolerable. If not, consider adding a resonator or sound-deadening material near the rear seat.
  • Cold start: Many Greddy setups are louder on cold start due to the engine’s rich fuel mixture. This is normal.

For a real-world sound demonstration, check out videos on YouTube – search for “Greddy Lexus IS exhaust sound test” to hear dozens of examples. Also, the Lexus official website can help you verify your model’s specifications before ordering parts.

Maintenance & Long-Term Tips

Keep the System Clean

Performance exhausts can discolor over time. Use a mild automotive soap and a soft cloth to clean the tips. Avoid abrasive pads that scratch the chrome or titanium finish. Some owners apply high-temp metal polish annually.

Inspect Hangers Every Oil Change

Rubber mounts wear out. Every 5,000 miles, visually check the hangers for cracks or sagging. Replace them if they look tired – worn hangers cause rattles and stress on exhaust welds.

Re-Torque After the First 500 Miles

After your initial install and a few heat cycles, go back under the car and check all flange bolts. It’s common for them to loosen slightly as gaskets compress. A quick re-torque prevents leaks and maintains a solid fit.

Consider a Pro Tune

If you’ve also installed an intake or header, a professional ECU calibration can optimize fuel and ignition timing to match the increased flow. Many Lexus tuners offer remote tuning options. A tune isn’t strictly necessary for an exhaust-only upgrade, but it can squeeze out extra horsepower and improve throttle response.

Frequently Asked Questions

Will a Greddy exhaust void my Lexus warranty?

In the US, the Magnuson-Moss Warranty Act protects you – the manufacturer cannot void a warranty just because you installed an aftermarket part. However, if the exhaust directly causes a problem (e.g., a cracked manifold due to improper installation), that specific repair may not be covered. Keep records and receipts.

Do I need to tune the car after installing the exhaust?

No, a Greddy cat-back or axle-back system does not require retuning. The ECU can adapt to the slightly different airflow within its normal parameters. If you change downpipes or headers, a tune becomes advisable.

How long does installation take?

Most first-timers spend 3–5 hours. Experienced mechanics can do it in 1.5–2 hours. Add an hour if you encounter rusted hardware.

Can I install the exhaust without cutting?

Yes – Greddy systems are designed as direct bolt-ons. You should not need to cut anything, as long as you remove the factory system properly. The only exception is if the old system is too corroded to unbolt; then you might need to cut the old pipe.

Conclusion

Installing a Greddy exhaust system on your Lexus IS is one of the most rewarding DIY projects you can undertake. The sound improvement transforms the driving experience, and the weight savings and flow gains give a mild performance bump. By following this detailed guide – with proper tools, safety measures, and meticulous installation – you’ll ensure a hassle-free upgrade that lasts for years. After the job is done, take your Lexus for a spirited drive and enjoy the new soundtrack.

For further reading, visit Road & Track for more automotive how-tos and aftermarket reviews.