Why Upgrade to a Borla Cat‑Back Exhaust on Your Honda Accord V6

Replacing the factory exhaust with a Borla cat‑back system is one of the most rewarding upgrades for a Honda Accord V6. The stock exhaust is designed to be quiet and cost‑effective, but it restricts flow and robs the engine of potential power. A Borla cat‑back system reduces back pressure, allowing exhaust gases to exit more freely. This can unlock a noticeable gain in horsepower and torque across the mid‑to‑high rpm range, while also shedding weight compared to the heavy factory components.

Beyond performance, Borla exhausts are renowned for their signature sound – a deep, aggressive tone without annoying drone on the highway. The Accord V6, especially the J‑series engine, responds particularly well to a free‑flowing exhaust, and Borla’s precision‑engineered piping and premium mufflers produce a refined note that enhances the driving experience. Additionally, a cat‑back upgrade improves engine cooling and can slightly increase fuel efficiency under normal driving conditions.

This guide covers every step of the installation process, from gathering tools to post‑installation checks. Whether you are a seasoned DIYer or a first‑time installer, following these detailed instructions will help you achieve a professional result and enjoy the full benefits of your new exhaust.

Tools and Materials Required

  • Jack and two jack stands (rated for at least 3 tons)
  • Socket set – metric, 10mm, 12mm, 14mm, 17mm, 19mm sizes
  • Combination wrench set – same metric sizes
  • Torque wrench – capable of 30–80 ft‑lb range
  • Cutting tool – reciprocating saw with metal‑cutting blade or angle grinder (for stubborn OEM exhaust removal)
  • Rubber mallet
  • Penetrating oil (e.g., WD‑40 Specialist or PB Blaster)
  • Safety glasses and mechanic’s gloves
  • Borla cat‑back exhaust system (part number 140423 for 2013–2017 Accord V6; verify fitment for your year)
  • Anti‑seize compound (optional but recommended for clamp bolts)

For torque specifications, refer to Borla’s included instructions or the official Borla website for the latest recommended values.

Preparation and Safety

Before touching any bolts, ensure you are working on a clean, level surface. The engine must be completely cool to avoid burns from hot exhaust components. Park the car, engage the parking brake, and chock the front wheels. Disconnect the battery negative terminal – this prevents any accidental short circuits and resets the ECU, which can help it adapt to the new exhaust more quickly during the first drive.

Rust and Corrosion Strategy

On vehicles driven in salted‑road climates, the fasteners holding the stock exhaust can be severely rusted. Spray all nuts and bolts with penetrating oil 30 minutes before you start. Pay special attention to the flange bolts at the catalytic converter connection and the rubber hanger mounts. If a bolt is seized, a combination of heat from a propane torch (used carefully away from fuel lines) and additional penetrating oil can break the rust bond.

Lifting the Vehicle Safely

Position the jack under the rear differential mount or a dedicated rear subframe jacking point (consult your owner’s manual). Lift the rear until you have at least 18 inches of clearance under the axle. Place jack stands under the reinforced frame rails just ahead of the rear wheels, then lower the vehicle onto the stands. Test stability by pushing the vehicle side‑to‑side before getting underneath.

Step‑by‑Step Installation Process

Step 1: Remove the Factory Exhaust

Start at the catalytic converter outlet. Using a 14mm or 17mm socket, loosen the two bolts that connect the factory mid‑pipe to the converter flange. If the bolts are extremely tight, apply more penetrating oil and wait a few minutes. On some years, there is a spring‑loaded flange – note that the factory uses no gasket here because the ball‑joint design seals itself. Try to keep the flange surfaces clean.

Next, detach the rubber hangers that support the factory mid‑pipe and muffler. Pull the hanger rods out of the rubber isolators using pliers if needed. For stuck hangers, soapy water or silicone spray will help them slide off. Once all hangers are free, the entire cat‑back section can be lowered and pulled out from under the car. If the exhaust is one long piece, you may need to cut it near the rear axle using a reciprocating saw or grinder – wear hearing protection and a dust mask for grinding dust.

Step 2: Inspect the Catalytic Converter Outlet

With the old exhaust removed, check the catalytic converter outlet pipe for any dents, rust, or damage. Clean the flange surface with a wire brush or sandpaper if there is corrosion. A clean mating surface is critical for a leak‑free seal with the new Borla system.

Step 3: Dry‑Fit the Borla System

Borla cat‑back systems come with several sections: an intermediate pipe, a rear muffler section, and sometimes a resonator section (depending on the kit). Lay out all parts on a clean towel and compare them to the factory piping. Do not tighten any clamps yet. Slide the intermediate pipe flange over the catalytic converter studs and hand‑tighten the nuts. Then loosely connect the rear muffler section using the supplied band clamps. The system should hang from the factory rubber isolators – check that the hanger rods align with the isolators correctly. If any rod is bent or misaligned, gently bend it with pliers to match.

Step 4: Final Adjustment and Torque Sequence

Once the system is hanging loosely, adjust the muffler tips so they are centered in the rear bumper cutout and the entire exhaust is evenly spaced around the underbody components. Keep at least a 1‑inch clearance from the spare tire well, rear sway bar, and fuel tank heat shield. After positioning is perfect, begin tightening. For flange nuts, use a torque wrench set to 35 ft‑lb (per Borla specification). For band clamps, tighten to 40 ft‑lb – overtightening can distort the slip‑joint and cause leaks. A torque wrench is essential here because the differential expansion of stainless steel and mild steel flanges requires precise clamping force.

Step 5: Secure Rubber Hangers

Ensure all rubber hangers are fully seated. Give each hanger a gentle tug to confirm it is locked in place. If the hanger rod has a notch, it should click into the isolator. For troublesome hangers, apply a thin layer of dish soap to the rubber – it will eventually dry and not affect long‑term hold.

Step 6: Double‑Check Everything

Before lowering the car, do a final inspection. Rotate each clamp to confirm it is not contact with anything. Check that the exhaust tip does not touch the bumper – stainless steel expands when hot and can melt plastic if too close. Start the engine briefly (in a well‑ventilated area) and listen for severe leaks. If you hear a loud hiss near the catalytic converter flange, tighten those nuts slightly more (but do not exceed 45 ft‑lb). If the hiss is at a slip‑joint, adjust that band clamp. After confirming no leaks, turn the engine off and let it cool.

Post‑Installation Checks and Break‑In

Lower the vehicle to the ground and reconnect the battery. Start the engine and let it idle while you listen from outside and inside the cabin. A proper Borla install should produce a refined, aggressive idle with no ticking or metallic vibrations. Take the car for a gentle 10‑minute drive, avoiding hard acceleration. This allows the exhaust to heat‑cycle and the clamps to settle. After the drive, park on level ground and re‑check all clamp bolts – stainless steel often requires a second tightening once the system has gone through its first heat cycle. Re‑torque to the same 40 ft‑lb.

Check for any contact between the exhaust and the underbody. Look for rubbed‑off paint or shiny spots on the piping. If contact occurs, loosen the affected clamp, reposition the pipe, and tighten again. Over the next 500 miles, the exhaust will develop a layer of carbon that darkens the stainless steel – this is normal and does not affect performance.

Troubleshooting Common Issues

Excessive Noise or Drone

If the system is noticeably louder than expected, check for leaks at flange connections and around the muffler inlet. A small leak can cause a high‑pitched rasp. Ensure all clamps are tight and the rubber hangers are not allowing the exhaust to transfer vibration to the chassis. For persistent drone, consider adding a Borla resonator (sold separately) to fine‑tune the sound.

Check Engine Light After Install

A cat‑back system should not trigger a check engine light because it does not alter the catalytic converter or the oxygen sensors. If a CEL appears, re‑examine the O2 sensor wiring and connectors – it is easy to accidentally damage a sensor wire when removing the old exhaust. If the wiring is intact, clear the code with an OBD2 scanner and monitor it. Driving the car for 50‑100 miles usually allows the ECU to adapt and the light stays off.

Exhaust Tip Misalignment

If the tips are not centered after tightening, loosen the rear band clamp and the hanger at the muffler. Gently push the muffler left or right, then retighten. You can also slightly bend the hanger rod using a large set of pliers (do not use a hammer – it can mar the stainless finish).

Maintenance and Long‑Term Care

Borla exhausts are made from T‑304 aircraft‑grade stainless steel and should last the life of the vehicle with minimal maintenance. However, to keep the system looking its best:

  • Clean the tips periodically with stainless steel polish and a microfiber cloth.
  • After winter driving, rinse the underside to remove road salt, which can cause surface discoloration.
  • Re‑tighten all clamps once a year, especially after the first few heat cycles.
  • Inspect rubber hangers for cracks or stretching every oil change – a broken hanger can allow the exhaust to sag and contact the driveshaft or fuel lines.

If you ever need to replace a component, Borla offers a million‑mile warranty on their exhausts – keep your purchase receipt and register your product on their website (Borla Support).

Performance Gains and Real‑World Results

On a Honda Accord V6 (J30/J35 series), a Borla cat‑back typically adds 8–12 horsepower and 10–15 ft‑lb of torque at the wheels, according to independent dyno tests. The peak gains occur between 4,000 and 6,500 rpm. Butt‑dyno improvements are noticeable – the engine revs more freely, especially when merging onto highways. The weight savings of approximately 15–20 pounds (depending on whether you removed a heavy factory resonator) also contribute to a slightly more responsive throttle.

Many owners report an average fuel economy improvement of 1–2 mpg on the highway when driving conservatively, thanks to reduced pumping losses. Of course, the sound itself is a huge part of the satisfaction – the Borla system gives the Accord V6 a soundtrack that matches its sporty character without being obnoxious.

Conclusion

Installing a Borla cat‑back exhaust on your Honda Accord V6 is a straightforward project that delivers immediate improvements in sound, performance, and driving enjoyment. By following this expanded guide – paying attention to torque specs, proper alignment, and post‑install checks – you can achieve a professional fitment that will reward you for years. Whether you chose the Touring or ATAK series, the process remains essentially the same. For more detailed fitment information or to purchase, visit Borla.com or consult the model‑specific Accord DIY forums for additional tips and community insights.