Loose Connections: Check all the connections between the test pipes and the exhaust system components, including the exhaust manifold, catalytic converter, and mufflers. Ensure all connections are tight and properly sealed.
Damaged Pipes or Components: Inspect the test pipes and other exhaust system components for any signs of damage, such as cracks, holes, or distortion. Replace any damaged parts.
Exhaust Manifold Gasket Failure: If the hissing sound is coming from the area of the exhaust manifold, the manifold gasket may be damaged or not properly seated. Replace the exhaust manifold gasket if necessary.
Header Leak: Ensure the collector flange of the headers are mating correctly with the mid pipes and the exhaust is completely sealed and clamped with no gaps.
Catalytic Converter Gasket: If the hissing sound is coming from the catalytic converter area, the catalytic converter gasket may be faulty. Replace the gasket and ensure the catalytic converter is properly installed.
Oxygen Sensor Hole: Make sure the oxygen sensors are screwed correctly into the test pipes.
If you are not confident in performing these checks, it is recommended to take your 350Z to a professional mechanic or exhaust shop for inspection and repair.
