Why Upgrade the S65 Exhaust System?

The S65 V8 engine found in the E9x M3 is renowned for its high-revving character and unique intake sound, but the factory exhaust system often leaves enthusiasts wanting more volume and a more aggressive tone. The Tubi Style Exhaust system offers a significant improvement in both sound and performance, providing a deeper, more resonant growl while reducing backpressure to unlock a few extra horsepower. This step-by-step guide walks you through the installation process, ensuring a smooth upgrade that will transform your driving experience.

Tools and Materials Needed

  • Socket set (metric, including 10mm, 13mm, 15mm, and 18mm sockets)
  • Combination wrench set (10mm, 13mm, 15mm, 18mm)
  • Torque wrench (capable of 20-80 ft-lbs)
  • Breaker bar or ratchet with extension
  • Jack and two jack stands (minimum 3-ton capacity)
  • Rubber mallet (for stubborn hangers)
  • Penetrating oil (e.g., WD-40 or PB Blaster)
  • Safety glasses and mechanic’s gloves
  • Flathead screwdriver (for prying hangers)
  • Exhaust gaskets (new, pre- or post-cat, as specified for your S65 application)
  • Tubi Style Exhaust system (confirm fitment for your specific M3 model year)
  • Shop rags and a pan for drips

Preparation: Safeguarding Your Work Area

Park your vehicle on a level, solid surface. Allow the engine and exhaust system to cool completely — working on hot components increases burn risk and makes bolts and hangers more difficult to manage. Disconnect the negative battery terminal to prevent any electrical shorts or accidental airbag deployment while working near the rear of the car. Gather all tools and lay out the new exhaust components to verify nothing is damaged or missing.

Step 1: Raising the Vehicle

Use the jack to lift the rear of the car. Position the jack stands under the factory reinforced jacking points on the rear subframe or designated lift points. Ensure the stands are fully engaged and the vehicle is stable before crawling underneath. For additional access, you may also lift the front slightly and place stands, but the rear alone is usually sufficient for a cat-back system.

Step 2: Removing the Stock Exhaust

Disconnect the Muffler Section

Apply penetrating oil to all bolts and hanger rubbers 10-15 minutes before removal. Starting at the rear, disconnect the muffler from the mid-pipe: there will be two slip-joint clamps or bolted flanges (depending on your S65’s specific model). Use the socket set with an extension to reach the upper bolts. On some models, you may need to remove rear bumper under-tray screws to access the top fasteners.

Remove Hangers and Brackets

Each muffler and pipe section is supported by rubber isolators. Pry the rubber hangers off the metal studs using a flathead screwdriver and a bit of silicone spray. If the studs are corroded, a rubber mallet can help free them. Carefully lower the stock muffler onto a moving blanket or cardboard — the factory unit is heavy (over 40 lbs for the rear section alone).

Remove Mid-Pipes (if included)

If your Tubi system is a full cat-back, you will also remove the mid-pipes. Unbolt the flanges near the catalytic converters (typically 13mm or 15mm). Note the position of oxygen sensor wires — you may need to unclip them from brackets before lowering the mid-pipes. Keep the gaskets; you will replace them with new ones during installation.

Step 3: Inspect and Prepare the New Tubi Exhaust

Unpack the Tubi Style Exhaust and inspect every component: the muffler body, connecting pipes, clamps, and any included hardware. Many Tubi systems feature polished stainless steel or titanium tips — ensure they are free of scratches. Line up the pieces on the ground in their approximate positions. Test fit the hanger rubbers and clamps to confirm orientation before lifting anything under the car. If the system comes with removable resonator sections, decide now whether to keep them for a quieter note or delete for maximum aggression.

Step 4: Installing the Tubi Style Exhaust

Attach the Mid-Pipes (if applicable)

Install new gaskets at the flange connections to the catalytic converters. Hand-tighten the bolts first, then torque them to the manufacturer’s specification (typically 25-35 ft-lbs). Do not fully tighten until all sections are aligned.

Mount the Rear Muffler

Slide the muffler into the rubber hangers. Use silicone spray to ease the rubber over the metal studs. The Tubi muffler is significantly lighter than the factory unit — be careful not to drop it. Once the muffler is hanging, attach the mid-pipe to muffler connection using the provided clamp. Usually this is a band clamp or a V-band clamp. Tighten it by hand first.

Align the Tips

With the system loosely connected, check the exhaust tip alignment relative to the rear bumper cutouts. The Tubi style often features larger, offset tips that should be centered and even. Adjust the position of the muffler on the hangers and the angle of the connecting pipes. Once satisfied, tighten the hanger bolts and clamp bolts to the recommended torque (typically 40-50 ft-lbs for band clamps).

Step 5: Torque All Connections Properly

This step is critical to prevent leaks and rattles. Retighten every flange bolt, clamp, and hanger fastener to the specified torque. Using a torque wrench ensures consistent clamping force without stripping threads. Pay special attention to exhaust gaskets — overtightening can crush them, causing leaks. Double-check all O2 sensor wiring is routed away from hot pipes and not pinched.

Step 6: Lower the Vehicle

Raise the car slightly with the jack to remove the jack stands, then lower it slowly. Check that the exhaust does not contact the chassis, heat shields, or driveline. Turn the steering wheel full lock left and right to ensure the exhaust clears the suspension components during movement.

Step 7: Start and Inspect

Reconnect the battery negative terminal. Start the engine and let it idle. Listen for any leaks — a hissing or sputtering sound indicates a gap at a flange or clamp. Use a soapy water spray around connections to identify leaks. When the system warms up, the notes will change; the Tubi exhaust should produce a deep, exotic sound that builds with RPM. Rev the engine gently to confirm no rattles or vibrations.

Check underneath for any drips (oil or coolant — unlikely but always wise). If the exhaust seems louder than expected at idle, allow it to cool, then re-check all clamp torque. A final visual inspection of tip clearance is recommended after the first drive cycle because heat can cause movement.

Post-Installation Break-In Period

Like any high-performance exhaust, the Tubi system will undergo a short break-in period. The sound may change slightly as residual packing material settles and the metal expands and contracts. Drive moderately for the first 100-200 miles, then retorque all fasteners after the initial heat cycles. This step ensures everything remains tight and leak-free.

Sound and Performance Gains

The Tubi Style Exhaust for the S65 is designed to release the engine’s full acoustic character. Expect a transformative improvement in tone — from a tame factory note to an aggressive, mechanical roar that intensifies above 4000 RPM. Many users report a seat-of-the-pants improvement in throttle response due to reduced backpressure, especially when combined with a tune. While peak horsepower gains are modest (typically 5-10 whp on a cat-back system), the driving enjoyment factor is substantial.

Maintenance Tips

  • Periodically inspect hanger rubbers for cracking — especially in cold climates.
  • Clean the polished tips with metal polish every few washes to prevent pitting.
  • Check clamp tightness every 6 months or after track events.
  • If you live in a region with road salt, consider applying anti-seize to flange bolts during installation for easier future removal.

Frequently Asked Questions

Will the Tubi Style Exhaust cause a check engine light?

No. A cat-back exhaust does not affect the primary oxygen sensors. Some systems include secondary O2 sensor spacers for cars with full header-back setups, but for a standard cat-back installation no CEL is expected.

Is the exhaust too loud for daily driving?

The Tubi design is known for being aggressive yet tolerable on the highway. It has minimal drone inside the cabin when cruising, but it is definitely louder than stock. If you have neighbors or early morning starts, be mindful — the cold start sequence can be quite boisterous.

Can I install this exhaust myself without a lift?

Yes, with jack stands the job is entirely DIY-friendly. The most challenging part is wrestling the heavy stock muffler out, but having a helper makes it easier. Allow 2-3 hours for a first-time install.

External Resources

For additional information on the Tubi Style Exhaust for the S65, visit the Directus product page for fitment details and sound clips. You can also read owner reviews on Bimmerpost’s E9x M3 section where many enthusiasts share installation tips and experiences. For technical torque specs, refer to the BMW TIS (Technical Information System) for factory specifications.

Conclusion

Installing a Tubi Style Exhaust on your S65-powered BMW M3 is one of the most rewarding upgrades for sound and driving enjoyment. By following this detailed guide, you can complete the installation in a few hours with basic tools. The result is a more aggressive, exotic exhaust note that perfectly complements the engine’s high-revving nature. Take your time with alignment and torquing, and you’ll enjoy a professional-quality installation that delivers the full benefit of this exceptional exhaust system.