The Nissan 240SX S13 remains one of the most popular platforms for budget-friendly performance builds, and swapping out the restrictive factory exhaust is one of the first upgrades most owners tackle. An XS Power exhaust system offers a significant improvement in flow, weight reduction, and sound while remaining affordable. This expanded guide covers every step of the installation process in detail, from tool selection to final tuning considerations, ensuring you get the most out of your new system without cutting corners.

Why Upgrade to an XS Power Exhaust on the S13?

The stock S13 exhaust is a serious bottleneck. Its small-diameter tubing (typically 2.25 inches), numerous crush-bends, and heavy mufflers restrict exhaust gas flow, choking horsepower and torque. By replacing it with an XS Power system—usually in 3-inch mandrel-bent tubing—you effectively reduce backpressure, allowing the KA24DE or SR20DET to breathe freely. The benefits include a measurable power gain (typically 10–15 horsepower on a naturally aspirated KA, more with forced induction), a deeper, more aggressive exhaust note, and a reduction in weight of roughly 15–20 pounds. For owners planning future upgrades like turbo kits or camshafts, a 3-inch exhaust system is essential preparation.

Tools and Materials Needed

Before you start, gather everything you will need. Having the right tools on hand prevents delays and damage to components.

  • XS Power Exhaust System Kit – Verify it includes all piping, muffler, hardware, and gaskets. Some kits include a downpipe or test pipe.
  • Socket wrench set with extensions – Metric sizes 10mm, 12mm, 14mm, and 17mm are most common for S13 exhaust bolts.
  • Breaker bar (1/2-inch drive) – For stubborn rusted nuts.
  • Penetrating oil (e.g., PB Blaster, Kroil, or Liquid Wrench) – Soak all exhaust fasteners the night before.
  • Jack and jack stands (two or four) – A low-profile jack works best for the S13.
  • Safety glasses and mechanic gloves – Exhaust systems are coated in road grime and sharp edges.
  • Exhaust hanger removal tool or pliers with long reach – The rubber hangers can be stubborn.
  • Anti-seize compound (copper or nickel-based) – Apply to all bolts and slip joints for future serviceability.
  • Gasket scraper or wire brush – To clean the manifold and catalytic converter flanges.
  • Torque wrench (optional but recommended) – For proper tightening of flange bolts.
  • Safety jack stands with 3-ton capacity – Never rely on the jack alone.
  • Creeper – Makes sliding under the car more comfortable.

Preparation: Setting Up Your Workspace and Vehicle

Proper preparation saves time and frustration. Follow these steps carefully:

  1. Park the S13 on a level, hard surface (concrete driveway or garage floor). Engage the parking brake.
  2. Loosen the lug nuts on the rear wheels (if you need access to the rear hangers). Then jack up the rear of the car using the factory jack points – the differential housing is the safest lift point for the rear on an S13.
  3. Place jack stands under the rear subframe or factory pinch welds (use a rubber pad or wood block to protect the pinch welds). Lower the car onto the stands. For full access, also jack up the front slightly and place stands under the front subframe.
  4. Allow the exhaust system to cool completely if the car was recently driven. Hot metal can cause severe burns.
  5. Spray penetrating oil on all exhaust bolts: manifold-to-exhaust flange, catalytic converter flanges, and any hanger bracket bolts. Let it soak for at least 15 minutes while you gather your tools.

Removing the Stock Exhaust System

The factory exhaust on the S13 is often corroded and seized. Patience and proper technique are key.

Step 1: Remove the Muffler and Rear Section

  • Using a socket wrench or breaker bar, remove the bolts connecting the muffler section to the mid-pipe (usually two bolts with 12mm or 14mm heads). If they are rusted, use gentle heat from a torch or apply more penetrating oil and wait.
  • Remove the rubber exhaust hangers using the hanger removal tool. Gently pry the rubber ring off the metal hanger studs. If the rubber is old and brittle, it may tear; have replacements on hand.
  • Lower the rear exhaust section and slide it out from under the car.

Step 2: Remove the Mid-Pipe and Catalytic Converter (if applicable)

  • Unbolt the mid-pipe from the catalytic converter (or test pipe) – typically two bolts at the flange. Again, soak with penetrating oil if stuck.
  • Remove the mid-pipe hanger. Some S13 models have a hanger near the driveshaft tunnel; disconnect it.
  • If your car retains the factory catalytic converter, unbolt it from the downpipe or manifold. On dual-cam KA24DE engines, the cat is integrated with a flex pipe. The XS Power system usually replaces everything from the manifold back, so the cat may need to be removed entirely.
  • Carefully lower the remaining stock components. They may be heavy – have a helper assist.

Step 3: Remove the Downpipe (if the kit includes a replacement)

  • Access the downpipe bolts from underneath. The downpipe connects to the exhaust manifold (four bolts on SR20DET, three on KA24DE). Use a 14mm deep socket and possibly a swivel adapter for tight angles.
  • Support the downpipe with a jack stand before removing the final bolts to prevent it from falling.
  • If your downpipe is rusted to the manifold, carefully use a chisel or a nut splitter. Do not force it to avoid cracking the manifold.
  • With all bolts removed, lower the downpipe and set aside.

Installing the XS Power Exhaust System

Now that the restrictive factory exhaust is gone, you can lay in the new system. XS Power exhausts are designed as direct-fit replacements, but some adjustments may be required for perfect alignment.

Step 1: Position the Exhaust Components

  • Begin by loosely assembling the system on the ground to verify all pieces are present: downpipe (if included), test pipe or cat replacement, mid-pipe, axle-back section, muffler, hangers, and hardware bag with bolts, nuts, washers, and gaskets.
  • Lift the downpipe into place first. Apply a thin coat of anti-seize to the manifold studs. Use the supplied gasket between the manifold and downpipe. Hand-tighten the nuts.
  • Attach the mid-pipe to the downpipe using the supplied flange gasket and bolts. Do not tighten fully yet; leave all connections loose to allow adjustment.
  • Slide the axle-back section (muffler) into position and connect it to the mid-pipe via a slip joint or flange. XS Power kits often use a slip joint with a band clamp. Apply anti-seize to the slip joint to prevent seizing.
  • Install the rubber hangers onto the new exhaust. The hanger holes should align with the chassis hooks. You may need to use a small flathead screwdriver to guide the rubber over the hooks. Some owners use silicone lubricant for easier installation.

Step 2: Adjust Alignment and Clearance

  • Now that everything is loosely connected, check clearances. The exhaust should not contact the transmission tunnel, driveshaft, rear subframe, or suspension arms. Rotate the muffler tip to center it in the rear bumper cutout.
  • Adjust the hanger positions. If a hanger bracket on the chassis is slightly off, you can gently bend it with a large pair of pliers or a pry bar. Do not force the exhaust – it should hang without strain.
  • Ensure the exhaust tip does not hit the bumper or frame under loading. A good rule of thumb is 1/2 inch clearance to any moving or body panels.
  • Check that the oxygen sensor (O2 sensor) bung is accessible. Many XS Power systems include a bung for the wideband O2 sensor. If your O2 sensor is unplugged, route the wiring carefully to avoid exhaust heat.

Step 3: Tighten All Fasteners

  • Starting from the manifold, torque the downpipe nuts to specification (typically 30–35 ft-lbs for KA24DE manifold studs). If using factory studs, use a torque wrench to avoid stripping.
  • Tighten the mid-pipe flange bolts to 25–30 ft-lbs.
  • Secure the band clamp over the slip joint. Do not overtighten – typically 20–30 ft-lbs is sufficient to prevent leaks without deforming the pipe.
  • Recheck all hangers to ensure the exhaust is properly supported. Loose hangers can lead to rattling.

Final Checks and Start-Up

Before lowering the car, perform a series of inspections to guarantee a trouble-free first start.

  • Leak check: With the car still on stands, have a helper gently rev the engine while you feel around each joint for exhaust puffs. Soapy water in a spray bottle can also help you spot leaks (bubbles indicate a gap). Tighten any leaking connections.
  • Clearance check: Shake the exhaust firmly by hand. It should not hit anything. If you hear metallic contact, adjust the hangers or pipe orientation.
  • O2 sensor: Ensure the sensor is plugged in and the wire does not touch the exhaust. Route it through the original clips if possible.
  • Heat shields: If your S13 still has factory heat shields over the exhaust tunnel, ensure they are reinstalled or that the new exhaust has adequate clearance (at least 1 inch) to prevent heat transfer to the chassis.
  • Lower the vehicle: Raise the car slightly, remove the jack stands, and lower onto the ground. Torque the rear lug nuts to spec (80 ft-lbs for S13).
  • Start the engine: The first startup will be louder than usual – this is normal. Listen for any unusual rattling or hissing. Let the exhaust heat cycle for a minute, then re-check the slip joint tightness (metal expands when hot).
  • Test drive: Take a short drive around the block, varying engine speed. Listen for drone, rattles, or any check engine light. If your O2 sensor was disturbed, the ECU may need a few drive cycles to adapt.

Tuning and Performance Considerations

A free-flowing exhaust changes the engine’s air/fuel ratio. On a naturally aspirated KA24DE, the ECU will partially compensate, but you may see a slight lean condition at wide-open throttle. For optimal gains and safety, consider these additional steps:

  • Install a wideband O2 sensor and gauge to monitor air/fuel ratios under load.
  • Upgrade the intake and tune the ECU (via ROM tune or standalone) to fully exploit the exhaust flow.
  • If you have a turbocharged SR20DET, a 3-inch exhaust will reduce exhaust gas temperature and improve spool. You should also upgrade the wastegate and boost controller to prevent overboost.
  • Consider wrapping the downpipe with DEI titanium wrap to reduce under-hood temperatures.

Common Installation Pitfalls and Solutions

Even experienced mechanics can encounter issues. Here are the most frequent problems and how to handle them:

  • Rusted fasteners: If a bolt snaps, you may need to drill out the stud and helicoil the flange. Avoid breaking manifold studs at all costs – use heat and penetrating oil liberally.
  • Exhaust hitting the driveshaft: The S13’s driveshaft is close to the exhaust tunnel. If you hear a clunking in gears, check clearance. A small dent in the tunnel can provide extra room, or you can slightly rotate the exhaust section.
  • Muffler tip too close to bumper: Loosen the axle-back clamp and slide it rearward or forward as needed. Some XS Power tips are angle-cut; rotate the pipe to center the tip.
  • Drone at highway speeds: 3-inch exhausts can produce drone in the 2500–3500 RPM range. Installing a resonator in the mid-pipe section (if not already present) can tame it without sacrificing flow.
  • O2 sensor wiring too short: The factory O2 sensor wire may need extension if the bung is relocated. Use a quality O2 sensor extension harness.

Maintenance Tips for Your XS Power Exhaust

To keep the system looking good and performing well, adopt a simple maintenance schedule:

  • Periodically inspect all rubber hangers for cracks or hardening – they degrade from heat and age. Replace them every 2–3 years.
  • Check all bolts and clamps for tightness after the first 500 miles, as exhaust components settle.
  • If the exhaust is stainless steel (most XS Power systems are T304 stainless), a mild polish with stainless cleaner will keep it from developing minor rust spots. For daily drivers in salt states, consider a ceramic coating (e.g., Jet-Hot) to prevent corrosion.
  • Watch for leaks at the flex section (if equipped) – a flex-pipe failure will cause a loud ticking sound. If it fails, replace it promptly.
  • After every oil change, give the underside a quick visual check for loose hangers or impact damage from road debris.

External Resources and Community Support

The S13 community is vast, and you can find detailed installation guides and troubleshooting threads online. Here are a few authoritative links:

Conclusion

Installing an XS Power exhaust system on your S13 240SX is a rewarding upgrade that unlocks noticeable power gains, improves throttle response, and gives your car a signature sound. By following this detailed guide – from preparation through final checks – you can complete the install in a weekend with basic hand tools and a little patience. The key is to take your time with rusted fasteners, double-check all clearances, and give yourself room to adjust alignment. Once everything is lined up and tightened, you’ll feel the difference the moment you push the throttle. Pair the exhaust with an intake and a tune, and your S13 will be ready for whatever the road – or the track – throws at it. Remember to perform periodic maintenance on your exhaust system to ensure it remains leak-free and performs at its peak for years to come.