Introduction: Why Upgrade to the AWE Tuning Exhaust on Your M133-Equipped Mercedes-AMG?

The AWE Tuning Exhaust system is a premier aftermarket upgrade for enthusiasts driving Mercedes-AMG models with the M133 engine – namely the A45, CLA45, and GLA45. This system is engineered to liberate significant horsepower and torque, reduce weight, and deliver a signature, aggressive exhaust note without drone. While the installation is straightforward for a competent DIYer, careful attention to detail ensures a perfect fit, optimal performance, and long-lasting durability. This comprehensive guide covers every step from preparation through final test drive, including torque specs, tool recommendations, and troubleshooting tips. Whether you’re a first-time installer or a seasoned mechanic, follow these instructions to achieve a factory-quality installation.

Note: Although the M133 engine is a Mercedes-AMG powerplant, these steps apply equally to BMW models with AWE Tuning systems (such as the M2, M3, and M4). The principles of exhaust removal and installation are nearly identical; only the specific hanger positions and bolt sizes differ. For this guide, we focus on the M133 platform.

Tools and Materials Needed

Having the right tools on hand will save time and prevent frustration. Gather the following before jacking up the car:

  • Socket set with extensions: Metric sizes 10mm, 13mm, 15mm, and 18mm. A deep socket for stud nuts is helpful.
  • Combination wrenches: Same sizes as sockets, plus a 21mm for exhaust hanger bolts if applicable.
  • Torx bits (T30, T40): Some exhaust components use Torx head bolts.
  • Breaker bar or ratchet with a long handle for stubborn bolts.
  • Penetrating oil (e.g., PB Blaster or WD-40 Specialist): Apply to exhaust flange bolts the night before.
  • Jack and jack stands (or ramps): A low-profile floor jack and two (or four) jack stands rated for the vehicle weight.
  • Torque wrench: ¾-inch drive for larger bolts, ⅜-inch drive for smaller fasteners.
  • Safety goggles and mechanic’s gloves.
  • Pry tool or flathead screwdriver for rubber hangers.
  • Exhaust hanger removal tool (optional but recommended) to avoid damaging rubber isolators.
  • Rubber mallet to tap stubborn slip joints.
  • Anti-seize compound for all threaded connections.
  • AWE Tuning Exhaust system – verify you have the correct application for your M133 model.
  • New exhaust gaskets and clamps (if provided or recommended by AWE).
  • Wire brush or sandpaper to clean mating surfaces.
  • Shop rags and a catch pan for any drips.

Pro tip: Check the forum for your specific vehicle (AWE Tuning official site often has vehicle-specific instruction sheets). For example, the M133 A45 requires different hanger positions than the CLA45.

Preparation: Safety, Workspace, and Vehicle Readiness

Safety First

Work in a well-ventilated garage or outdoors. Allow the exhaust to cool completely – it can reach over 400°F during operation. Never work under a vehicle supported only by a jack; always use jack stands. Chock the front wheels if lifting the rear, and set the parking brake.

Vehicle Preparation

Start with a cold engine. If you’ve driven recently, wait at least an hour. Apply penetrating oil to all exhaust flange nuts and bolts that will be removed (downpipe connections, midpipe, muffler hangers). Let it soak while you arrange tools. For best results, loosen fasteners when the vehicle is still warm (not hot) to break the bond.

Workspace Setup

Clear the area of obstacles. Have a tray or cardboard to lay out the AWE exhaust components and keep hardware organized. Take a photo of the stock exhaust before removal – it helps during reassembly of hangers.

Step 1: Lift the Vehicle Securely

Position the jack under the factory jacking point (refer to your owner’s manual). Lift the rear of the vehicle until the wheels are about 12 inches off the ground. Place two jack stands under the designated lift points – typically the rear subframe or side frame rails. Gently lower the car onto the stands and test for stability by shaking the car. If you need access to the entire exhaust (from downpipe to tips), you may also lift the front using stands. For most M133 cars, you only need the rear elevated to reach the muffler and midpipe connections.

Safety note: Never rely solely on a jack. Use jack stands rated for at least 2,200 lbs each.

Step 2: Remove the Stock Exhaust System

2.1 Disconnect the Downpipe Connection

Locate the bolts connecting the downpipe to the midpipe or center resonator. Use a 13mm or 15mm socket with an extension. If bolts are rusted, apply more penetrating oil and use a breaker bar. Remove the nuts or bolts entirely. For M133 applications, there are usually two bolts at the flange. Carefully separate the flanges; they may be stuck. Gently tap with a rubber mallet if needed. Place a rag over the opening to keep debris out.

2.2 Remove the Midpipe and Resonator (if applicable)

Follow the exhaust rearward. Depending on your system, you may need to unbolt a center support bracket. Use the same socket sizes. Set aside hardware.

2.3 Detach the Rear Muffler

Support the stock muffler with a jack or a helper. Remove the bolts securing the muffler to the chassis – typically four 13mm bolts or Torx T30 heads. Then, gently pry the rubber exhaust hangers off the metal hanger studs using a pry tool or a specialized hanger removal tool. The muffler may be heavy (around 35 lbs), so have a partner grab it as the last hanger releases. Carefully lower it to the ground.

2.4 Remove Remaining Hangers and Brackets

Some M133 models have an exhaust valve actuator (if equipped). Disconnect the electrical connector and remove the actuator carefully. Set aside.

Important: Inspect the stock exhaust hangers – if they are cracked or perished, replace them with new ones (AWE Tuning includes high-quality replacements in most kits).

Step 3: Prepare the AWE Tuning Exhaust for Installation

Unbox the new exhaust and lay out all components. Verify you have the correct system: downpipe-back or cat-back? M133 systems are typically cat-back. Check for the following parts:

  • Muffler assembly (single or dual exit depending on model)
  • Midpipe section
  • Exhaust tips (if separate)
  • Mounting hardware: bolts, nuts, washers, and clamps (often T-bolt clamps)
  • New gaskets (check if pre-installed or included)
  • Hanger set (rubber isolators and metal brackets)
  • Installation manual

If any flanges have protective plastic caps, remove them. Apply a thin coat of anti-seize to all threads of bolts and nuts that will be used – this prevents galling and makes future removal easier.

Adjustment Note: AWE Tuning exhausts are designed to fit precisely, but you may need to slide the components slightly for perfect alignment. Do not fully tighten clamps until the entire system is hung.

Step 4: Install the AWE Tuning Exhaust System

4.1 Mount the Rear Muffler First

Position the muffler under the car and lift it into place. Attach the rubber hangers to the chassis studs – push them on by hand or use a small pry bar. For M133 cars, there are typically three hangers on the muffler. Ensure the hangers are fully seated and not twisted.

4.2 Connect the Midpipe Section

Slide the midpipe into the muffler inlet. Most systems use a slip joint with a T-bolt clamp. Do not tighten yet. Insert the midpipe’s front flange into the downpipe connection. Use new gasket if provided. Hand-tighten the flange bolts.

4.3 Attach the Center Support Bracket (if included)

Align the midpipe support bracket to the factory mounting point. Use the original bolts or new ones. Torque to spec (typically 18-20 Nm).

4.4 Install the Exhaust Tips

If your AWE kit includes separate tips, slide them onto the muffler outlets. Adjust them so they sit flush with the bumper cutout (usually 5–10 mm gap). Tighten the set screws per manufacturer instructions – often 5 Nm. Do not overtighten on polished tips to avoid scratching.

4.5 Final Alignment and Tightening Sequence

With all components loosely connected, stand back and check the overall alignment. The exhaust should be centered in the rear bumper cutout and not touch any metal parts. Wiggle each section to ensure it can move freely. Then, tighten in this order:

  1. Downpipe to midpipe flange bolts (torque to 30 Nm for M133).
  2. All T-bolt clamps (torque to 8–10 Nm).
  3. Rear muffler hanger bolts (if any – typically 13mm bolts to 20 Nm).
  4. Center support bracket.
  5. Exhaust tip set screws.

Recheck all fasteners after tightening. Note: Torque specs vary; always refer to the AWE Tuning instruction sheet for your specific system.

Step 5: Reattach Exhaust Hangers and Actuators

If your stock vehicle had an exhaust valve actuator (for drone reduction or sport mode), you may need to transfer it to the AWE system. Some AWE kits use the factory actuator; others delete it. If included, install the actuator bracket and connect the electrical plug. Ensure the cable is routed away from heat sources and moving parts. Then, verify all rubber hangers are seated correctly. Give each hanger a firm tug.

Check for clearance around the driveshaft, rear axle, and body panels. Rotate the driveshaft by hand if possible to confirm no contact. AWE Tuning designs their exhausts with enough clearance, but shift the system if needed before final tightening.

Step 6: Lower the Vehicle and Perform a Visual Inspection

Carefully remove the jack stands and lower the car. With the car on the ground, re-tighten all accessible bolts – especially the downpipe flange. The weight of the vehicle can cause slight shifts in alignment. Also check that the exhaust tips are still perfectly centered. If not, loosen the T-bolt clamps slightly, adjust, and retighten. Then start the engine only after a final undercar inspection for loose tools or objects.

Step 7: Test Drive and Sound Evaluation

Start the engine and let it idle for 30 seconds. Listen for any ticking or hissing sounds that indicate a leak at a flange or clamp. If you hear a leak, use a soapy water spray bottle around connections to identify bubbles. Tighten or adjust as needed. Check for rubbing noises by turning the steering wheel lock-to-lock (if applicable) and by revving the engine gently.

Once satisfied, take the car on a short test drive (5 minutes) to heat cycle the exhaust. After the drive, let it cool and re-torque all bolts and clamps – metals expand and settle. The AWE Tuning system will produce a deeper, more aggressive tone under load, especially in Sport mode. Expect a noticeable increase in volume but with minimal drone on the highway. If you experience excessive drone, check that the system isn’t interfering with the body or that the actuator is functioning properly.

Important: New exhaust systems may emit a light smoke or smell during the first few heat cycles as packing material and oils burn off. This is normal. If it persists, inspect for leaks.

Additional Tips and Considerations

Performance Gains

The AWE Tuning exhaust on the M133 can add 8–12 peak horsepower and 10–15 lb-ft of torque, along with a weight savings of roughly 10–15 lbs over stock. Combined with a tune, gains increase.

Emissions and Noise Regulations

Check local laws regarding aftermarket exhausts. AWE Tuning systems are designed to be street legal with removable silencers in some cases. The Touring Edition is quieter than the Track Edition. Choose accordingly.

Warranty

AWE Tuning offers a limited lifetime warranty on materials and construction (excludes tips and clamps). Register your product after installation.

Troubleshooting Common Issues

  • Bolts won't loosen: Apply heat with a propane torch (away from fuel lines) and use penetrating oil.
  • Exhaust tips touch the bumper: Loosen rear clamps, adjust forward/backward, retighten.
  • Drone at certain RPMs: Ensure the exhaust valve is connected and functioning. Some M133 cars benefit from a resonator delete or aftermarket valve controller.

Conclusion

Installing the AWE Tuning Exhaust on your M133-equipped Mercedes-AMG is a rewarding upgrade that transforms both sound and performance. By following this step-by-step guide – from thorough preparation and safe lifting to careful alignment and final torque checks – you can achieve a professional-grade installation in your own garage. The immediate result is a more engaging driving experience with a distinctive exhaust note that announces your arrival. For additional resources, refer to the AWE Tuning official website for vehicle-specific instructions, or visit popular forums like the AMG forums for community support. If you encounter any difficulties, do not hesitate to consult a professional exhaust shop. Enjoy the new sound!