Why Install Headers on Your 370Z

Upgrading the headers on your Nissan 370Z – whether it's a base model or the sportier Nismo – is one of the most effective bolt-on modifications for unlocking extra horsepower and a more aggressive exhaust note. The factory exhaust manifolds are restrictive, designed for noise suppression and cost efficiency. Aftermarket headers, particularly equal-length long-tube designs, improve exhaust flow, reduce backpressure, and allow the VQ37VHR engine to breathe properly. The result is a noticeable bump in mid-range and top-end power, often between 15–25 wheel horsepower when paired with a tune, along with a deeper, more refined tone.

While the installation is a moderately challenging DIY project, it can be completed in a weekend with the right tools, patience, and attention to detail. This guide covers the complete process for both 370Z Base and Nismo models, highlighting specific differences you'll encounter (such as the Nismo's additional bracing and different Y-pipe configuration). Always consult your specific header manufacturer's instructions and torque specifications before starting.

Tools, Parts & Safety Gear

Having everything ready before you lift the car will save you from frustrating trips to the tool box. In addition to the new headers, you'll need the following:

  • Tools: 3/8″ and 1/2″ drive socket set (10mm, 12mm, 14mm, 17mm, 19mm), a flex-head ratchet or wobble extensions for tight engine bay access, a torque wrench (capable of 30–50 ft-lb), combination wrenches (14mm and 17mm), gasket scraper or razor blade, wire brush, penetrating oil (PB Blaster or Kroil), breaker bar or impact wrench for stubborn bolts
  • Lifting equipment: Low-profile floor jack and a set of four jack stands (minimum 3-ton capacity). Ramps are not recommended because you need full wheel-off access
  • New parts: Header gaskets (often included with headers, but buy OEM or quality replacements), new exhaust manifold studs and nuts if the originals are corroded, copper anti-seize compound, and new exhaust gaskets for the Y-pipe connection
  • Safety: Safety glasses, mechanic gloves, and ear plugs (working under the car is loud)
  • Optional but helpful: O2 sensor socket (7/8″ or 22mm), ratcheting wrench set, and a telescoping magnet for dropped bolts

Preparing the 370Z for Header Installation

Work Area and Vehicle Setup

Park the car on a level concrete floor. Allow the engine to cool completely – headers and exhaust components get extremely hot, and working on a warm engine increases the risk of burns and warped flanges. Disconnect the negative battery terminal and tuck it away to prevent accidental shorts and to reset the ECU after the job is done.

Raising and Securing the Vehicle

Because you need access to the underside of the engine bay and the exhaust system, the car must be raised high enough to work comfortably. Using the factory jack points, lift the front of the car and place jack stands under the front subframe or designated lift points. For additional safety, leave the floor jack supporting the car once the stands are set. Remove both front wheels if you need extra room to reach upper header bolts, though many installs can be done with the wheels on if you turn them to full lock. The Nismo model's front bumper lip is lower – be careful not to scrape it when jacking.

Removing Underbody Panels and Heat Shields

Remove the large under-engine cover (if equipped) by pulling out the plastic push pins and 10mm bolts. On Nismo models, there is an additional front underbody brace that must be unbolted and lowered. You may also need to remove the strut tower brace for better access to the passenger-side header bolts. Set all hardware aside in a labeled bag.

Removing the Factory Headers

Disconnecting the Exhaust System

Start by unbolting the Y-pipe (front exhaust pipe) from the factory manifolds. The factory connection uses two spring bolts at each flange – use a penetrating oil on these threads a few hours before you begin. If the bolts are rusted, apply heat carefully with a propane torch to break the corrosion. Once the Y-pipe is free, lower it slightly and tie it up with a wire or bungee cord to the subframe. You do not need to completely remove it, but it must be out of the way to access the header outlet flanges.

Removing the O2 Sensors

The factory headers have two oxygen sensors (one per bank) mounted in the exhaust stream. Unplug the sensor connectors from the chassis harness – they are located near the firewall on each side. Use an O2 sensor socket or a 7/8″ wrench to unscrew the sensors from the manifolds. Be gentle: these sensors are expensive and can be damaged if forced. Apply anti-seize to the threads when reinstalling later.

Unbolting the Headers

The headers are held to the cylinder heads with a row of nuts (10mm or 12mm, depending on year). Access to these nuts is tight, especially on the driver's side near the steering column and on the passenger side near the intake manifold. Use a combination of short sockets, wobble extensions, and flex-head ratchets. Work from the center outward, loosening each nut slightly before removing them completely. There are 8 studs per header. Once all nuts are removed, gently rock the header to break it free from the gasket. On a Nismo, the passenger side header may require removing a small heat shield connected to the block – do this first.

Tip: If a stud comes out with the nut, don't panic – just remove the stud and replace it. It's common for the studs to be seized. Use a stud remover or double-nut method to extract broken studs. If the head of a nut strips, use a quality six-point socket or a bolt extractor socket.

Cleaning the Mating Surfaces

With the factory headers off, use a gasket scraper and wire brush to clean the cylinder head deck. Remove all old gasket material and carbon deposits. Be careful not to scratch the aluminum head surface. Wipe the area with a clean rag and brake cleaner. Do the same for the Y-pipe flanges if reusing them, though it's best to install new gaskets there as well.

Installing the New Headers

Gasket Placement and Anti-Seize

Place the new header gaskets onto the studs. Most aftermarket headers use a multi-layer steel (MLS) gasket – these are marked “this side up” or have a directional arrow. Ensure the gasket is seated flat against the head. Apply a small amount of copper anti-seize to the threads of all studs and to the header bolt holes (if they are threaded). This prevents galling and makes future removal easier.

Positioning and Bolting the Headers

Slide the new header into position from below. It's easier to install the header from the bottom of the car with the Y-pipe still loose. Align the header flange over the studs and press it onto the gasket. Start all nuts by hand to ensure they are cross-threaded. Work in a crisscross pattern, tightening gradually to a final torque of 35–40 ft-lb (check your header manufacturer's spec – some require less). A torque wrench is critical here: overtightening can warp the header flange or strip the studs, while under-tightening causes exhaust leaks.

Nismo Note: The Nismo model has additional chassis bracing near the transmission that may interfere with the passenger header. You may need to temporarily lower or remove this brace to allow the header to slide into place. This is normal – just unbolt and reinstall after the headers are bolted.

Reinstalling the O2 Sensors and Heat Shields

Screw the O2 sensors back into the new header bungs (usually located in a similar position as factory). Torque them to 30 ft-lb (or hand-tight plus half a turn). Do not overtighten – O2 sensor threads are thin. Reconnect the sensor wiring harnesses. If your headers came with metal heat shields or thermal wrap, install them now per the instructions. Refit any factory heat shields that were removed.

Reconnecting the Exhaust System

Attaching the Y-Pipe

Lift the Y-pipe back into position and align it with the header flanges. Use new gaskets and the original spring bolts or aftermarket hardware. Tighten the bolts just until the springs are partially compressed – this allows for thermal expansion. Torque to 30–35 ft-lb for non-spring connections. Double-check that the Y-pipe is not binding or touching the subframe; if it is, loosen and reposition.

Reinstalling Underbody Panels and Braces

Bolt back any underbody braces (especially on the Nismo) and the plastic undercover. Do not leave any panels loose – they can fall off at speed. Reinstall the strut tower brace if removed.

Final Steps and Post-Installation Checks

Reconnecting the Battery

Reconnect the negative battery terminal. The ECU will need a little time to relearn idle and fuel trims after the header change. You may want to perform an idle re-learn procedure (turn ignition on for 10 seconds without starting, then start and let idle for 10 minutes). Check for any warning lights.

Inspection for Leaks and Noise

Start the engine and let it idle. Listen for any ticking or hissing sounds that indicate an exhaust leak. Use a glove or a rag to cover the tailpipe – if you hear a “popping” sound from under the hood, you have a gasket leak. Spray a small amount of soapy water around each header flange – bubbles will reveal leaks. Tighten any loose nuts slightly (check torque again after the first heat cycle).

Test Drive and Torque Recheck

Take the car for a short drive, letting the engine come up to operating temperature. Listen for rattles and check for any CEL related to O2 sensors (if you deleted sensors, you'll need a tune to turn off the light). After the first heat cycle, let the engine cool and re-torque the header nuts to spec – they often settle slightly.

Performance Gains and Next Steps

With headers installed, your 370Z will feel noticeably livelier, especially above 3,500 RPM. The sound will be deeper and louder, but not obnoxious if you retain your factory cats or use high-flow cats. For maximum gains, consider an ECU tune (OFT, UpRev, or ECUTEK) to optimize fuel and timing for the improved flow. You can expect 15–20 hp on a base model, slightly less on a Nismo due to its already less restrictive Y-pipe. Z1 Motorsports and Concept Z Performance offer proven header-and-tune packages.

Common Issues and Troubleshooting

  • Stubborn bolts: Apply penetrating oil the night before. Use a propane torch as a last resort – avoid open flames near fuel lines.
  • Wiring harness clearance: Ensure the O2 sensor wires are routed away from the headers and not pinched between the header and block.
  • Check engine light: If you have a post-cat O2 sensor code, you may need spacer (defouler) or a tune to delete the rear sensors.
  • Rattling: Make sure the headers do not contact the steering shaft, frame rails, or motor mounts. Use header wrap or ceramic coating to reduce heat soak on nearby components.

Final Thoughts

Installing headers on a 370Z is a rewarding project that delivers real performance and a more exciting exhaust note. Whether you drive a base or Nismo model, the process is largely the same once you account for the extra bracing on the Nismo. Take your time, use quality tools, and don't skip the torque wrench. Your engine will thank you with years of reliable, spirited driving. For detailed torque specs and model-year-specific tips, always cross-reference with the factory service manual or reputable online resources like The370Z.com forums.