Why Upgrade Your S62 Exhaust?

The S62 engine, found in the E39 M5 and Z8, is a naturally aspirated V8 known for its high-revving character and robust torque curve. While the factory exhaust system is well-engineered for refinement and emissions compliance, it introduces significant restrictions upstream. By replacing the restrictive OE components with a properly designed aftermarket exhaust, owners routinely unlock 15-25 horsepower at the wheels without touching internal engine parts. Beyond the dyno-proven gains, an aftermarket system can reduce curb weight by 20–40 pounds, sharpen throttle response, and deliver an acoustic experience that matches the engine’s motorsport heritage.

This guide walks through the complete installation process for an aftermarket exhaust on an S62-powered vehicle. Whether you are aiming for maximum power, a deeper exhaust note, or a combination of both, the steps outlined here will help you achieve a clean, leak-free installation that performs reliably for years.

Choosing the Right Aftermarket Exhaust for the S62

Not all aftermarket exhausts are created equal. Selecting the correct system is critical to hitting your target power gain and sound profile. Consider these factors before buying:

Exhaust Configuration Options

  • Cat-back systems – Replace piping from the catalytic converters rearward, offering moderate power gains (10–15 hp) and tone improvement while retaining OE cats. Ideal for street-driven cars that need to pass emissions.
  • Axle-back systems – Replace only the mufflers and tailpipes. Primarily a sound upgrade with minimal power improvement (5–10 hp) but easier installation.
  • Header-back or full exhaust – Includes long-tube headers, mid-pipes, and a cat-back section. This option delivers the highest gain (25–35 hp) but requires ECU tuning, has higher cost, and may trigger check-engine lights without proper calibration.

Material and Construction

Stainless steel (304 grade) offers corrosion resistance and long life, while titanium is lighter and produces a distinct metallic note. Look for mandrel-bent tubing to maintain consistent diameter and avoid flow restrictions. Welded joints should be smooth and free of slag.

Reputable Manufacturers for S62 Exhausts

Trusted brands such as Eisenmann, Supersprint, and Remus produce S62-specific systems. For the best performance-to-value ratio, systems from Vibrant Performance are also worth considering. Always verify that the system includes all required gaskets, clamps, and hardware.

Tools and Materials Needed

Gather the following before lifting the car:

  • Aftermarket exhaust system (with gaskets, bolts, and clamps)
  • Socket wrench set (metric: 10mm, 13mm, 15mm, 17mm, 18mm, 21mm)
  • Breaker bar or impact wrench (for stubborn fasteners)
  • Jack and jack stands (rated for the vehicle’s weight)
  • Penetrating oil (e.g., WD-40 Specialist Rust Release or Liquid Wrench)
  • Torque wrench (range 20–80 ft-lb)
  • Safety goggles and heavy-duty gloves
  • Exhaust hanger removal tool (or large flathead screwdriver + pliers)
  • Anti-seize compound (copper- or nickel-based)
  • Oxygen sensor socket (for systems that reuse OE sensors)
  • Wire brush or sandpaper for cleaning mating surfaces

Preparation Steps

Proper preparation prevents damage to components and reduces install time. Perform these checks before laying a hand on the exhaust:

  • Park the vehicle on a level, hard surface. Engage the parking brake firmly.
  • Allow the engine and exhaust system to cool completely. Working on hot pipes can cause burns and warped flanges.
  • Disconnect the negative battery terminal. This prevents accidental shorts when working near sensors or if a tool contacts a starter wire.
  • Spray all exhaust flange bolts and rubber hanger isolators with penetrating oil. Let it soak for at least 10–15 minutes.
  • Raise the vehicle using the factory jack points. Place jack stands under the reinforced lift pads; never rely solely on a hydraulic jack.

Removing the Old Exhaust System

Removing the stock exhaust on an S62 is straightforward but requires patience with corroded hardware. Follow this sequence:

  1. Support the exhaust. Use a transmission jack or a second set of jack stands to support the weight of the exhaust so it does not hang on the hangers.
  2. Detach oxygen sensors. If your system includes O2 sensors in the mid-pipes, unplug the connectors and use an oxygen sensor socket to remove them. Label each sensor (bank 1 / bank 2, upstream / downstream) to avoid mix-ups later.
  3. Remove rear muffler section. Loosen the bolts at the muffler connection to the mid-pipe. Use an exhaust hanger tool to pry the rubber isolators off the hanger hooks. Slide the muffler back and lower it carefully.
  4. Remove mid-pipe or X-pipe. Unbolt the flanges at the catalytic converters (or headers if applicable). The S62 factory mid-pipe is heavy; have a helper support it as you disengage the hangers.
  5. Remove catalytic converter assembly (if replacing headers). For full header-back systems, unbolt the cats from the manifolds. This step often requires a long extension and a swivel socket due to tight clearance.
  6. Inspect old system. Check for pinhole rust, broken welds, or collapsed internal baffles. It is often helpful to compare the weight of the stock parts against the new components to confirm weight savings.

Installing the Aftermarket Exhaust

Install the new exhaust in the reverse order of removal, but follow these best practices to ensure a perfect fit and maximum performance:

  1. Clean all mating surfaces. Use a wire brush or sandpaper to remove carbon buildup and old gasket material from flange faces. A clean seal prevents exhaust leaks.
  2. Install new gaskets. Most aftermarket systems supply new graphite or metal gaskets. Place them dry; never add sealant on top of a gasket unless the manufacturer explicitly requires it.
  3. Assemble the system loosely. Hand-tighten all flange bolts and clamps. This allows you to adjust alignment before torquing everything down. Pay special attention to:
    • Exhaust tip clearance to the rear bumper cutout.
    • Distance between the piping and the driveshaft, subframe, and rear differential.
    • Height of the muffler so it does not contact the spare tire well or underbody bracing.
  4. Attach oxygen sensors. Install the sensors into the provided bungs. Apply a small amount of anti-seize to the sensor threads (if not pre-coated). Do not overtighten – typical torque is 30 ft-lb. Route the wiring away from hot pipes and moving suspension components.
  5. Tighten all fasteners to spec. Use a torque wrench. Typical values: M8 flange bolts 18 ft-lb, M10 flange bolts 30–35 ft-lb, V-band clamps to manufacturer specification. Re-check after the first heat cycle.
  6. Reattach rubber hangers. Lubricate the hanger hooks with a dab of dish soap or rubber grease to ease installation. Ensure each hanger is fully seated.

Post-Installation Checks and First Start

Before lowering the car, perform a thorough inspection:

  • Rotate the steering wheel lock-to-lock while looking for any contact between the exhaust and steering linkage or tie rods.
  • Bounce the rear suspension by hand to ensure the exhaust clears the axle and trailing arms under load.
  • Verify that heat shields are reinstalled (if removed) and are not contacting the new system.

Reconnect the battery and start the engine. Let it idle for two to three minutes while checking for leaks. Use a gloved hand to feel around each flange and joint for puffs of escaping gas. If you hear a ticking noise or feel suction, tighten the corresponding fastener slightly. Do not drive the car until all leaks are resolved.

ECU Tuning and the Aftermarket Exhaust

Installing a cat-back or axle-back exhaust on the S62 does not typically require ECU tuning, because the engine management system can compensate for small changes in backpressure. However, if you have installed a header-back system that removes the primary catalytic converters, the O2 sensors will report a lean condition at idle and may trigger a check-engine light (DTC P0420 / P0430). To fully exploit the increased flow and avoid drivability issues, consider a reflash from a reputable tuner such as Dinantronics or ESS Tuning. A proper tune can add an additional 10–15 horsepower on top of the exhaust gains and smooth out the air-fuel ratio across the rev range.

Test Drive and Break‑In Procedure

After confirming no leaks, take the car for a low-stress test drive. Keep the following in mind:

  • Drive gently for the first 50–100 miles to allow the exhaust to heat-cycle properly. This helps gaskets seat and bolts to settle.
  • Vary the engine speed; avoid sustained high-rpm runs during break-in.
  • After the first 25 miles, re-torque all exhaust flange bolts and check the hanger positions. Metal expansion and contraction can loosen fasteners.
  • Listen for buzzes or rattles. If the exhaust contacts the body or driveline, adjust alignment or add a rubber spacer to the hanger.

Common Pitfalls and How to Avoid Them

Even experienced DIYers can encounter issues. Here are the most frequent problems and solutions:

  • Stuck fasteners. Rusted bolts are common on older S62s. Heat the bolt area with a propane torch (avoid rubber isolators) to break the bond, or use a nut splitter as a last resort. Replace all removed fasteners with new OE or stainless steel hardware.
  • Exhaust drone. Some aftermarket systems produce a low-frequency boom at cruising speeds. If drone is objectionable, consider adding a Helmholtz resonator or swapping to a system with larger mufflers.
  • Check engine light after installation. This usually indicates an oxygen sensor that was not reconnected, a damaged sensor wire, or a system that deletes the secondary cats. Use a scan tool to read the code and address the root cause.
  • Poor fitment. Not all budget systems align perfectly. If the exhaust contacts the subframe, loosen the entire system, re-align from front to back, and tighten gradually. In rare cases, you may need to elongate a bolt hole or use a shim.

Maintenance and Long-Term Care

An aftermarket exhaust can last the life of the vehicle with minimal maintenance:

  • Clean the tips regularly with metal polish to prevent pitting and carbon build-up.
  • Inspect rubber hangers annually; replace any that are cracked or hardened.
  • Check flange bolts at every oil change. Re-torque if you notice any looseness.
  • If your system uses a slip-on design with clamps, apply a thin bead of high-temperature copper RTV to the joint during initial installation to prevent soot seepage.

Conclusion

Installing an aftermarket exhaust on your S62 is a gratifying upgrade that delivers tangible horsepower gains, weight reduction, and an aural experience befitting a high-performance V8. By selecting a quality system, preparing the work area properly, and following the step-by-step removal and installation procedures outlined here, you can complete the job in a weekend with basic mechanical skills. Whether you keep the car street-friendly with a cat-back or go all-in with headers and a tune, the result is a more responsive, exhilarating S62 that truly lives up to its legendary reputation.