Upgrading the exhaust system on your Mitsubishi Lancer Evolution can dramatically enhance both its performance and auditory appeal. Installing an HKS exhaust system, renowned for quality and precision engineering, offers improved exhaust flow, reduced backpressure, and a more aggressive exhaust note that complements the Evo's sporty character. This comprehensive DIY guide will take you through each step of installing an HKS exhaust system safely and effectively, ensuring you maximize the benefits of this upgrade.

Understanding the Benefits of an HKS Exhaust System

Before diving into the installation process, it’s important to understand why upgrading to an HKS exhaust system is a popular choice among Mitsubishi Lancer Evolution enthusiasts:

  • Performance Gains: HKS exhausts are engineered to optimize exhaust gas flow, reducing backpressure and improving horsepower and torque output.
  • Enhanced Sound: The distinctive deep and sporty exhaust note accentuates the Evo’s aggressive character without being overly loud or droning at cruising speeds.
  • Durability and Quality: Constructed from high-grade stainless steel or titanium in some models, HKS exhausts resist corrosion and wear, ensuring long-lasting performance.
  • Weight Reduction: Many HKS exhaust systems are lighter than stock units, helping improve overall vehicle weight distribution and handling.
  • Customization Options: Some HKS exhausts offer modular designs or interchangeable mufflers, allowing you to tailor sound and performance to your preferences.

Tools and Parts Needed for Installation

Having the right tools and parts on hand before starting the job will make the installation process smoother and safer. Gather the following:

  • HKS Exhaust System Kit: Verify that the kit is specific to your Mitsubishi Lancer Evolution model and year to ensure proper fitment.
  • Socket Set and Ratchet: A comprehensive set including metric sizes (typically 10mm to 19mm sockets) is essential.
  • Combination Wrenches: Metric sizes matching the socket set will help in tight spaces.
  • Jack and Jack Stands: A hydraulic floor jack and sturdy jack stands rated for your vehicle’s weight.
  • Penetrating Oil (e.g., WD-40 or PB Blaster): Useful for loosening rusted or seized bolts.
  • Rubber Mallet: Helps gently coax exhaust components into place without damaging flanges or pipes.
  • Torque Wrench: Essential for tightening bolts to the manufacturer’s specified torque settings.
  • Safety Gear: Safety gloves to protect your hands from sharp edges and hot surfaces, and goggles to shield your eyes from rust or debris.
  • Exhaust Hanger Removal Tool (Optional): Makes removing rubber hangers easier, especially if they’re stiff or brittle.
  • Anti-Seize Compound: Applying this to bolts during reassembly helps prevent future rust and makes future removal easier.

Preparation Before Installation

Proper preparation is critical to a successful exhaust installation. Follow these steps carefully:

1. Choose a Suitable Workspace

Park your Mitsubishi Lancer Evolution on a flat, stable surface such as a driveway or garage floor. Ensure there is ample lighting and ventilation since exhaust fumes can be hazardous. Avoid working on soft or uneven ground that could compromise jack stand stability.

2. Allow Your Car to Cool Down

If the vehicle has been recently driven, allow the exhaust system and engine bay to cool completely. Exhaust components can reach extremely high temperatures and cause serious burns.

3. Engage Safety Measures

Apply the parking brake and place wheel chocks behind the rear wheels to prevent any accidental movement. Disconnect the negative terminal of the battery to avoid electrical shorts or accidental starts during installation.

4. Lift the Vehicle Safely

Use your hydraulic jack to lift the front and/or rear of the car, depending on which sections of the exhaust you need to access. Position jack stands under the manufacturer’s recommended lift points to securely support the vehicle. Never rely solely on the jack to hold the car while working underneath.

5. Apply Penetrating Oil

Spray penetrating oil liberally on all exhaust mounting bolts, nuts, and clamps that you will be removing. Allow it to soak for 10-15 minutes to help loosen rust and corrosion, reducing the risk of breaking bolts during removal.

Step-by-Step Guide to Removing the Old Exhaust System

Carefully removing the factory exhaust is crucial to prevent damage to the vehicle and prepare for a smooth installation of the new HKS exhaust components.

1. Identify Exhaust Components

Familiarize yourself with the layout of the stock exhaust system. Key sections include:

  • Downpipe (connects to the turbocharger outlet)
  • Catalytic converter
  • Mid-pipe or center pipe
  • Muffler and tailpipe
  • Rubber hangers and mounting brackets

2. Remove Exhaust Bolts and Clamps

Using the socket set and wrenches, begin loosening the bolts that connect the exhaust system sections, typically starting near the downpipe or catalytic converter flange. If bolts are stubborn or show signs of rust, apply more penetrating oil and allow it to soak longer. Use a breaker bar for extra leverage if necessary.

3. Detach Exhaust Hangers

Carefully remove the rubber hangers that support the exhaust system from the chassis. An exhaust hanger removal tool can make this process easier. If not available, pry the hangers off gently using a flathead screwdriver, taking care not to damage the rubber.

4. Lower the Exhaust Components

With all bolts and hangers removed, carefully lower the old exhaust system from the vehicle. It’s helpful to have an assistant hold one end while you work on the other to avoid dropping or bending pipes.

5. Inspect Mounting Points and Surrounding Areas

Check the exhaust flanges, studs, and mounting brackets for damage or excessive rust. Clean any mating surfaces with a wire brush to ensure a proper seal when installing the new exhaust.

Installing the HKS Exhaust System

Now that the old exhaust is removed and the mounting points are prepared, proceed with installing your new HKS exhaust system.

1. Test Fit Components

Lay out all HKS exhaust components and compare them to the removed stock parts. Familiarize yourself with each section and the order of assembly. Test fit sections under the vehicle to ensure proper alignment with mounting points.

2. Attach the Downpipe to the Turbo Outlet or Catalytic Converter

Begin installation at the front of the exhaust system. Align the downpipe flange with the turbo outlet or catalytic converter flange. Use new gaskets if provided to ensure a proper seal. Hand-thread the bolts to avoid cross-threading, then tighten partially.

3. Connect Mid-Pipes and Center Pipes

Next, connect the mid-pipe or center pipe sections, sliding the pipes together where designed for slip-fit connections. Ensure the orientation of the slip joints and any clamps follows the manufacturer’s instructions. Do not fully tighten clamps yet, allowing for adjustment during final alignment.

4. Install the Muffler and Tailpipe

Attach the muffler section and tailpipe last, securing them to the existing exhaust hangers. Use the rubber mallet to gently tap sections into place if needed, ensuring a snug fit without forcing components.

5. Secure Exhaust Hangers and Mounting Brackets

Reattach the exhaust hangers and brackets to support the new system firmly. Ensure the exhaust does not contact the body panels, suspension components, or brake lines, which could cause rattling or damage.

6. Tighten All Bolts and Clamps Properly

Using a torque wrench, tighten all exhaust flange bolts, clamps, and mounting hardware to the HKS manufacturer’s specified torque values. Over-tightening can warp flanges or damage threads, while under-tightening may cause leaks or rattles.

7. Apply Anti-Seize Compound

Before final tightening, apply a thin layer of anti-seize compound to bolts and studs to prevent corrosion and ease future removal.

Post-Installation Checks and Break-In

After installation is complete, perform the following checks to ensure the exhaust system is functioning as intended.

1. Visual Inspection

Examine the entire exhaust system for proper clearance around all components. Verify there is no contact with the chassis, suspension, or brake lines.

2. Leak Test

Start the engine and listen carefully for any exhaust leaks, which may sound like ticking or hissing near flange connections. If leaks are detected, shut off the engine and re-tighten bolts or clamps as needed.

3. Monitor for Unusual Noises or Vibrations

Take the car for a short, cautious test drive. Listen for rattling, clunking, or drone sounds that may indicate loose components or improper fitment.

4. Re-Torque Bolts After Heat Cycles

After the first few heat cycles (driving the car until the exhaust reaches operating temperature and then cooling down), re-check and re-torque all bolts and clamps. Thermal expansion can cause fasteners to loosen initially.

Additional Tips for a Successful Installation

  • Work with a Partner: Having an assistant can make handling long or heavy exhaust sections safer and easier.
  • Use Quality Replacement Gaskets: Always replace exhaust gaskets during installation to ensure airtight seals.
  • Keep the Work Area Clean: Dirt or debris between flanges can lead to leaks.
  • Document the Process: Take photos during disassembly to aid reassembly and troubleshooting.
  • Check Local Regulations: Ensure your exhaust upgrade complies with local noise and emissions laws.

Safety Tips During Exhaust Installation

  • Always wear safety gloves and goggles to protect against cuts, burns, and debris.
  • Work in a well-ventilated area to avoid inhaling harmful exhaust fumes.
  • Never work under a vehicle supported only by a jack; always use sturdy jack stands placed on solid ground.
  • Keep a fire extinguisher nearby, especially when working with penetrating oils or in enclosed spaces.
  • Disconnect the battery to prevent accidental electrical shorts or injuries.

Conclusion

Installing an HKS exhaust system on your Mitsubishi Lancer Evolution is a rewarding project that can unlock improved engine performance and deliver a thrilling exhaust note. While the process requires careful preparation, proper tools, and attention to detail, following this step-by-step guide will help you complete the installation confidently and safely. With your new exhaust system in place, you’ll enjoy not only enhanced power delivery but also the unmistakable sound that defines the Evo’s sporty heritage. Take your time, adhere to safety precautions, and soon you’ll be back on the road with a more exhilarating driving experience.