Upgrading your Subaru Forester with a cold air intake is one of the most effective ways to unlock extra horsepower and throttle response without complicated engine modifications. The TurboXS cold air intake is specifically engineered for Subaru platforms, offering a balance of improved airflow, heat isolation, and a straightforward installation process. This comprehensive guide will walk you through every step of the installation, from gathering tools to performing final checks, so you can confidently complete the job in your own garage. Whether you’re a seasoned DIYer or a first-time modifier, following these instructions precisely ensures a reliable, leak-free setup that delivers real performance gains.

Why Choose the TurboXS Cold Air Intake for Your Subaru Forester?

Before diving into the installation, it helps to understand what makes this intake kit a popular choice for Forester owners. The TurboXS intake uses a mandrel-bent aluminum tube that maintains a smooth inner surface, reducing air turbulence compared to the restrictive factory airbox. The cone filter is positioned in a cooler area of the engine bay, drawing in denser air that contains more oxygen. This increase in oxygen allows the engine to burn fuel more efficiently, resulting in gains of 5–10 horsepower and 3–7 lb-ft of torque on stock engines, depending on the model year and supporting modifications. The kit also includes a high-flow reusable air filter, eliminating the need for frequent replacements. For a deeper dive into the science behind cold air intakes, check out TurboXS’s official product page for specifications and dyno charts.

Tools and Materials Needed

Having every tool on hand before you start prevents frustrating trips to the hardware store mid-installation. Below is the full list with additional detail on why each item is important.

  • TurboXS Cold Air Intake Kit – Ensure you have the correct part number for your Subaru Forester generation (typically 2009–2013 or 2014–2018, depending on your kit). Verify all components are present: intake tube, cone filter, clamps, mounting brackets, and any vacuum line adapters.
  • Socket set (metric, 8mm–14mm) – Most bolts on the Forester’s intake system are 10mm, 12mm, and 14mm. A ratcheting socket wrench speeds up the work.
  • Combination wrench set (metric) – Useful for reaching tight bolts that a socket can’t access, especially near the throttle body.
  • Flathead screwdriver – For prying off hose clamps and loosening spring-type clamps on the factory intake.
  • Phillips screwdriver – Some plastic brackets or clips may require a Phillips head.
  • Torque wrench (½-inch drive, range 10–50 ft-lb) – Critical for tightening the throttle body clamp and battery terminal to manufacturer specs without over-tightening.
  • Shop towel or rag – Use to plug the throttle body opening while the factory intake is removed; prevents debris from entering the engine.
  • Safety glasses – Always wear eye protection when working under the hood, especially when disconnecting spring clamps or removing bolts near the fan.
  • Gloves (nitrile or mechanic’s) – Optional but recommended to keep hands clean and avoid cuts from sharp edges.
  • Penetrating oil (optional) – If bolts are rusted or stubborn, a quick spray of WD-40 or PB Blaster helps loosen them.

Safety Precautions

Working on a vehicle always involves some risk. Follow these precautions to ensure a safe installation:

  • Park on a level surface and engage the parking brake. Chock the rear wheels for extra security.
  • Allow the engine to cool completely – at least 30 minutes after shutdown – to avoid burns from hot manifold or coolant lines.
  • Disconnect the negative battery terminal before touching any electrical components or sensors. This prevents accidental short circuits and resets the ECU to learn the new intake.
  • Keep loose clothing, jewelry, and long hair away from moving parts like the radiator fan (which can turn on even with the engine off).
  • Work in a well-ventilated area, especially if you need to run the engine after installation to check for leaks.

Preparation

Park your Subaru Forester on a flat surface and turn off the engine. Let it cool down sufficiently – the exhaust manifold and turbo housing (if equipped) can stay hot for an hour. While you wait, gather all tools and lay the TurboXS kit components on a clean workbench. Remove any large items from the engine bay that could obstruct access, such as aftermarket strut tower bars or engine bay dress-up covers. Read the entire installation manual that came with your kit to familiarize yourself with the specific routing and bracket placements for your Forester’s engine (normally aspirated 2.5L or turbocharged 2.0L/2.5L).

Step 1: Remove the Engine Cover

The plastic engine cover on most Foresters is held by four or five rubber grommets or bolts. Using a socket wrench with a 10mm socket (or a Phillips screwdriver for some models), remove the bolts or gently pull up on the cover to dislodge the rubber mounts. Carefully lift the cover off and set it aside in a safe place where it won’t be scratched. This step gives you clear access to the throttle body and factory airbox assembly.

Step 2: Disconnect the Battery

Using a wrench (typically 10mm), loosen the nut on the negative battery terminal and slide the clamp off the post. Move the cable away from the terminal and secure it with a zip tie or piece of tape to prevent accidental contact. Disconnecting the battery resets the ECU, which helps the engine adapt to the increased airflow of the new intake. Wait at least five minutes before proceeding to allow capacitors in the ECU to discharge completely.

Step 3: Remove the Factory Air Intake System

Now the real work begins. The factory intake system consists of an airbox, a resonator chamber (often on the front bumper/ fender area), a connecting tube, and the hose leading to the throttle body.

  1. Locate the hose clamp that connects the intake tube to the throttle body – it’s usually a spring clamp or a screw-type clamp. Use a flathead screwdriver to loosen it, then carefully slide the hose off the throttle body. Immediately stuff a clean shop towel into the throttle body opening to prevent dirt or small bolts from falling into the engine.
  2. Unclip any electrical connectors attached to the intake tube, such as the mass airflow sensor (MAF) or intake air temperature sensor (IAT). On some Forester models, the MAF sensor is integrated into the factory airbox. Gently press the release tab and pull the connector straight out – do not yank on wires.
  3. Remove the bolts or screws that secure the airbox to the chassis. Typically there are two 10mm bolts at the bottom and sometimes an additional bolt near the fender. Lift the entire factory airbox and tube assembly out of the engine bay. You may need to tilt it to clear the radiator fan shroud.
  4. If your Forester has a resonator chamber attached to the fender well, unscrew or unclip it and remove it as well. This improves airflow and reduces restriction.

Set all factory parts aside – you may want to keep them if you ever return the car to stock.

Step 4: Install the TurboXS Cold Air Intake

This is the core of the installation. The TurboXS kit is designed to mount directly in place of the factory system with minimal modification.

  1. Before placing the new intake tube, inspect the throttle body opening. Remove the shop towel and wipe any oil residue with a clean rag. The tube must create an airtight seal to avoid unmetered air leaks.
  2. Slide the large silicone coupler (provided in the kit) onto the throttle body. Use a small amount of silicone spray or dish soap on the inside of the coupler to ease installation. Do not use grease that can degrade rubber.
  3. Position the TurboXS aluminum intake tube so that it aligns with the coupler and the filter location. The tube typically routes downward toward the lower bumper area or behind the headlight, depending on the kit. Use the supplied brackets and hardware to secure the tube to existing mounting points – usually a bolt hole near the battery tray or the inner fender. Tighten the bracket bolts to 8–10 ft-lb (hand tight plus a quarter turn).
  4. Slide the coupler over the throttle body and the intake tube. Both ends should have the clamp in the correct position. Tighten the clamp at the throttle body first: use a screwdriver or a 7mm socket to snug it, then torque to 3–5 ft-lb (do not overtighten, as aluminum threads can strip). Finally, tighten the clamp on the intake tube side.
  5. If your kit includes a vacuum line fitting (for the crankcase ventilation or PCV system), connect the supplied hose between the intake tube and the engine’s breather port. Use the included barb fittings and clamps. This step is critical for proper crankcase evacuation and to prevent oil residue from coating the filter.
  6. Reattach the MAF sensor and IAT sensor if they were removed. On many TurboXS kits, the MAF sensor mounts directly into the intake tube via a rubber grommet. Align the sensor’s orientation arrow with the airflow direction (usually marked on the tube). Tighten the small screws that hold the sensor – be careful not to crush the grommet.

Take a moment to double-check that all clamps and brackets are tight, and that the intake tube does not touch any hot engine components (exhaust manifold or turbo heat shield). A clearance of at least 1 inch is recommended.

Step 5: Connect the Air Filter

Attach the provided cone filter to the end of the intake tube. The filter will either slide over the tube and be secured with a clamp, or screw onto a threaded adapter. Use the included clamp and tighten it securely – enough to hold the filter in place but not deform the filter’s flange. Verify that the filter is positioned in a cool air stream (usually near the front bumper or behind the fog light area). If your kit came with a heat shield, install it now between the filter and the engine to block radiant heat from the exhaust manifold. Follow the kit’s instructions for heat shield mounting brackets.

Step 6: Reconnect the Battery

With the intake fully installed, reconnect the negative battery terminal. Tighten the clamp until it cannot rotate on the post – torque to about 8–10 ft-lb. Do not overtighten, as it can crack the battery case. Turn the key to the “ON” position (engine off) for 10 seconds, then turn it off. This allows the ECU to power up and start learning the new airflow parameters.

Step 7: Replace the Engine Cover

Place the engine cover back onto the engine. It should snap over the rubber grommets or bolt back into place. Ensure it doesn’t pinch any wires or hoses underneath. Tighten the cover bolts to hand-tight – overtightening can crack the plastic. The cover is mostly cosmetic and does not affect performance.

Final Checks and Testing

Before starting the engine, visually inspect every connection:

  • Are all clamps tight?
  • Is the filter securely attached and not touching any moving parts?
  • Is the MAF sensor wiring properly routed away from heat sources and moving belts?
  • Are there any tools or rags left in the engine bay?

Start the engine and let it idle for 30 seconds. The idle may be slightly rough at first as the ECU adjusts, but it should smooth out within a minute. Check for any whistling or hissing sounds – these indicate an air leak. If you hear a leak, shut off the engine and recheck all clamps and couplers. A small amount of intake noise is normal; cold air intakes typically produce a throaty growl under throttle. Rev the engine gently to 2000–3000 RPM and listen for irregularities. Once satisfied, take the car for a short test drive, accelerating smoothly. Notice improved throttle response and a deeper intake sound. The check engine light should not come on. If it does, stop and verify all sensor connections and look for vacuum leaks. For more troubleshooting tips, Subaru owners often share their experiences on Subaru Forester owners forums.

Troubleshooting Common Issues

Even with careful installation, a few issues can arise. Here’s how to handle them:

  • Check Engine Light / MAF code: Often caused by a dirty or damaged MAF sensor. Clean it with MAF sensor cleaner, and ensure the sensor is seated correctly and the wiring harness is intact. Some intakes require recalibration of the ECU; a simple battery disconnect for 15 minutes often cures the code.
  • Whistling noise at idle: Usually a small air leak at the coupler or throttle body. Tighten clamps. If the silicone coupler is not fully seated, loosen and reposition it.
  • Filter sucking against something: The filter may contact the inner fender or bumper. Adjust its position or use supplied spacers to keep it away from obstructions.
  • Idle drop or stalling: The ECU may need a few drive cycles to learn. If it persists, check the vacuum line connection – an unplugged breather hose can cause erratic idle.

Maintenance and Care

The TurboXS cone filter is reusable. Clean it every 15,000–20,000 miles (or more often if you drive on dusty roads). Use a dedicated air filter cleaning kit – spray cleaner, let it soak, rinse with water (from the inside out), and re-oil lightly with filter oil. Over-oiling can contaminate the MAF sensor, so apply oil sparingly. Every 30,000 miles, inspect the intake tube and clamps for cracks or looseness. Also wipe the MAF sensor with MAF-safe cleaner to maintain accurate readings. Proper maintenance ensures the intake performs at its peak for years.

Performance Benefits and Expected Gains

After installation, you’ll notice immediate improvements in throttle response and a more aggressive engine note. On a stock Forester 2.5L naturally aspirated engine, expect gains of 5–8 horsepower and 3–5 lb-ft of torque at the wheels. Turbocharged models see larger gains (10–15 hp) because the intake reduces restriction on the turbo inlet. To fully realize these gains, consider pairing the intake with a performance tune. Many owners report that the intake alone makes the car more responsive in daily driving, especially merging onto highways. For a more technical breakdown of intake tuning, refer to Engine Basics’ guide on airflow.

Conclusion

Installing a TurboXS cold air intake in your Subaru Forester is a rewarding project that delivers tangible performance improvements without breaking the bank. By following the steps outlined above – from disconnecting the battery to final checks – you can complete the installation in under two hours with basic hand tools. The key is attention to detail: secure all clamps, route hoses away from heat, and respect the ECU’s learning period. With the intake in place, your Forester will breathe easier, sound more aggressive, and respond more eagerly to every touch of the throttle. For further reading on optimizing your Subaru’s air intake system, check out Subaru’s official accessories page and forums like NASIOC where thousands of enthusiasts share their experiences. Enjoy the drive – you’ve earned it.