Upgrading the intercooler on your Mitsubishi Lancer Evolution IX is one of the most effective modifications for improving power output and thermal management on a turbocharged platform. The factory intercooler works adequately at stock boost levels, but as you push the Evo 9 harder—whether on a track or during aggressive street driving—charge air temperatures rise, leading to timing retard and lost performance. A Greddy intercooler kit offers a higher core volume, better fin density, and more efficient airflow routing. This guide provides a thorough, step-by-step installation process, along with essential tips to ensure your Greddy intercooler delivers maximum cooling and reliability. We cover everything from tool selection and bumper removal to boost leak testing and post-installation tuning considerations. By following these instructions, you can complete the swap in your home garage with confidence and immediately feel the difference in throttle response and sustained power.

Tools and Materials Needed

Having the right tools on hand before you start saves frustration and downtime. While the Greddy kit includes most hardware and silicone couplers, you will need a standard set of automotive hand tools and a few specialty items to do the job correctly.

  • Greddy intercooler kit (part number depends on your specific core size and piping configuration)
  • Socket set – metric, 8mm to 19mm, with extensions and a universal joint
  • Wrenches – combination wrenches in 10mm, 12mm, 14mm, and 17mm
  • Screwdrivers – flathead and Phillips, including a long-reach flathead for hose clamps
  • Trim removal tools – plastic pry tools to avoid scratching paint when removing bumper cover clips
  • Torque wrench – ¼-inch and ⅜-inch drive, capable of torque values from 5 to 50 ft-lb
  • Hose clamps – T-bolt style are recommended over worm-gear for high-boost applications
  • Heat-resistant tape or silicone paste to prevent silicone couplers from slipping
  • Safety goggles and gloves
  • Jack and jack stands – working at ground level is possible but raising the front allows easier bumper removal
  • Boost leak tester – homemade or purchased, to verify seal after installation
  • Anti-seize compound – for stainless steel hardware that contacts aluminum

Preparing Your Evo 9 for the Upgrade

Before touching any tools, park the car on a level, dry surface and disconnect the negative battery terminal. Allow the engine to cool completely—at least one hour after a drive—so you are not working near hot coolant or oil. Remove the engine under-tray (plastic splash shield) by unscrewing the 10mm bolts and plastic push-pins. This gives you access to the lower bumper support and the factory intercooler outlet pipes. It is also a good time to inspect your front bumper cover for cracked paint or broken mounting tabs; a damaged bumper can complicate reinstallation.

Step 1: Removing the OEM Intercooler

The factory side-mount intercooler (SMIC) on the Evo 9 lives in the passenger-side front bumper area, connected to the turbo outlet and intake pipe via rubber hoses.

  1. Remove the front bumper cover. Start by unscrewing the fasteners along the top edge near the headlights, the wheel well liners, and the bottom edge. Use the plastic trim tools to gently pop the bumper off its clips. Set the bumper cover aside in a safe place, ideally on a blanket to avoid scratches.
  2. Disconnect the intercooler inlet and outlet hoses. Loosen the hose clamps on the turbo-to-intercooler pipe and the intercooler-to-throttle body pipe. Label each hose if you plan to reuse them, though the Greddy kit replaces these with larger-diameter silicone couplers.
  3. Unbolt the intercooler mounting brackets. The factory intercooler is held in place by two or three 12mm bolts on the radiator support and lower mount. Remove these and carefully wiggle the intercooler out through the bumper opening. It may require tilting to clear the metal bracket.
  4. Inspect the stock intercooler. Note any oil residue inside the charge pipes—this can indicate turbo seal wear. Clean the area where the intercooler sat, removing any debris.

Step 2: Preparing the Greddy Intercooler

Open the Greddy kit and verify all components: the core, end tanks, piping, couplers, clamps, and mounting hardware. Read the manufacturer’s instructions completely; while this guide covers universal steps, your specific kit may have unique routing.

  • Inspect the intercooler core for bent fins or shipping damage. Straighten any minor fin deformities with a small pick or fin comb.
  • Test-fit the piping loosely to understand the routing. The Greddy kit for the Evo 9 typically runs the hot pipe from the turbo to the driver-side end tank and the cold pipe from the passenger-side end tank to the throttle body. Mark each pipe with tape for orientation.
  • Assemble the silicone couplers and T-bolt clamps onto each pipe. Use a thin layer of silicone paste inside the coupler ends to ease assembly and prevent leaks.
  • Install the intercooler core into the vehicle before attaching the piping. Slide the core into place from the front, aligning the mounting tabs with the factory holes on the radiator support. The Greddy core is taller than stock, so you may need to slightly trim the plastic lower grille or bumper support—check fitment before any cutting.

Step 3: Installing the Greddy Intercooler

With the core loosely positioned, secure it using the supplied brackets. Most Greddy kits use existing chassis holes—no drilling required. Tighten the mounting bolts to 18 ft-lb using a torque wrench to avoid stripping the aluminum.

  1. Route the hot pipe from the turbocharger compressor outlet to the driver-side intercooler inlet. Use the supplied silicone 90-degree coupler at the turbo connection. Ensure the pipe does not rub against the radiator fan shroud or the A/C lines.
  2. Route the cold pipe from the passenger-side intercooler outlet up to the throttle body. This pipe often passes over the transmission bellhousing; check for clearance. Adjust the pipe rotation to avoid contact with the intake manifold.
  3. Tighten all T-bolt clamps to the manufacturer’s specification—usually 5-7 ft-lb when using the supplied small screwdriver-style fastener. Do not overtighten; silicone can bulge and cause blow-offs under boost.
  4. Verify all joints are seated fully. Push each pipe into the coupler until it bottoms out before tightening.

Step 4: Reinstalling the Front Bumper and Piping

With the intercooler secure, reattach the bumper cover. Carefully align the tabs and clips, then press firmly until each snaps into place. Re-install all screws and push-pins. If the intercooler protrudes forward, you may need to trim the lower bumper opening for clearance—use a Dremel or utility knife, removing material from the inside lip that is not visible when installed.

The Greddy kit may require relocating the factory horn or washer fluid reservoir. Check for contact between the piping and these components. If needed, use a zip tie or a fabricated bracket to move them slightly. Reconnect the battery and turn the ignition to the ON position (engine off) to verify no electrical interference.

Step 5: Final Checks and Boost Leak Test

This is the most important step before starting the engine. A single loose clamp can cause a massive boost leak, poor idle, and potential lean conditions.

  • Inspect all connections – tighten any clamp that feels loose. Pay special attention to the turbo outlet and throttle body couplers.
  • Perform a boost leak test. Use a boost leak tester that caps the turbo inlet and pressurize the system to 15-20 psi using a regulated air source. Listen and feel for hissing. Common leak points: couplers not fully seated, BOV flange, and throttle body shaft. Soapy water in a spray bottle helps locate tiny leaks.
  • Check fluid levels – you may have bumped a coolant hose or power steering line during the install. Top off as needed.
  • Re-inspect the bumper and wheel well liners – ensure no tools or parts left behind.

Step 6: Test Drive and Performance Validation

Start the engine and let it idle for 2-3 minutes. The intercooler system is passive during idle, but listen for any unusual air whistling that indicates a leak. Rev the engine gently to 2500 rpm and hold—this can help seat the couplers. If your Evo 9 has an aftermarket boost gauge or AccessPort, watch the boost pressure during a short test drive. A properly installed intercooler should allow the turbo to reach target boost more quickly and maintain it without flutter.

Take the car on a 15-minute drive including both highway and hard acceleration runs. Check the intercooler core temperature after driving: it should be noticeably cooler to the touch on the outlet (cold) side than the inlet (hot) side. If both sides are similar temperature, the intercooler is not flowing efficiently—verify pipe routing and core orientation.

Understanding the Performance Gains

A larger, front-mounted intercooler like the Greddy reduces intake air temperature by 20-40°F under sustained boost, depending on ambient conditions. Cooler air is denser, allowing the engine to run more timing and potentially more boost without knock. On a stock-turbo Evo 9, this translates to 10-20 whp gains with no other changes, plus reduced heat soak after repeated pulls. The core’s larger surface area also improves consistency on track days. For cars with upgraded turbos or raised boost, the intercooler becomes even more critical to prevent detonation.

Common Mistakes to Avoid

  • Overtightening clamps – T-bolt clamps can cut into silicone if over-tightened. Use a torque wrench or just snug them with a small ratchet; you should be able to twist the coupler slightly with effort.
  • Routing pipes too close to hot surfaces – keep charge pipes at least 1 inch away from the exhaust manifold, turbo, and radiator hoses. Use heat wrap or reflective tape if clearance is tight.
  • Forgetting to trim the bumper – forcing the bumper over the new intercooler can crack paint or stress the core. Take time to trim plastic where indicated.
  • Skipping the boost leak test – even a small leak can cause rough idle and reduced power. Always test before the first drive.
  • Ignoring throttle body alignment – the cold pipe can push against the throttle body if not oriented correctly, causing binding. Confirm the throttle plate opens fully with the pedal.

Post-Installation Tuning Considerations

While the Greddy intercooler itself does not require a tune, the cooler intake air will alter the engine’s volumetric efficiency. If your Evo 9 has an aftermarket ECU or a reflash (e.g., EcuTek or COBB AccessPort), you should log intake air temperature (IAT) and knock correction values. Lower IATs may allow slightly more ignition advance. If you are running a boost controller, consider raising boost by 1-2 psi to take advantage of the improved cooling—but only after verifying that fuel and timing maps are safe. For stock ECUs, the factory knock sensors will automatically adjust; no retune is strictly necessary, but a professional calibration can extract more power safely.

Conclusion

Installing a Greddy intercooler on your Evo 9 is a weekend project that pays dividends in consistent performance and lower intake temperatures. By following this detailed guide, you ensure each step—from bumper removal to boost leak testing—is handled correctly. The result is a more responsive, reliable turbo system that holds up to hard driving. Whether you’re chasing lap times or simply want better daily drivability, this upgrade is one of the best investments for your Evolution.

For further reading on intercooler theory and turbocharger matching, check out Greddy’s official site for product specs, the EvoM forums for user experiences, and this technical overview of intercooler efficiency for a deeper understanding of the upgrade’s benefits.