Pull the battery connector from its negative terminal, block the rear wheels, and hit the parking brake. Lift up your car's front, put it on jackstands, and take off the cooling shield that's under the engine if you have it. Soak the fasteners on the exhaust components with penetrating oil, let it work its way into the bolts. Take the exhaust Y-pipe off your car, then disconnect the oxygen sensors. Soak the bolts holding the exhaust heat shields on, then take off the bolts at the front of the catalytic converters to get them out of the exhaust manifolds. You'll need to empty all the engine coolant, plus separate the coolant lines from the top and rear side of the 350Z's engine whenever you take out either intake manifold. Undo the nuts or bolts connecting the manifold to the heads, and take the manifold and gasket apart. Scrape off and clean all the old gasket material and carbon from where both parts connect. Place the new exhaust manifold gaskets on top of the
Cylinder Head studs with the gaskets dot marked side facing up. Thread the nuts/bolts through the manifold, then use a wrench to fasten them step by step with the torque we require. Put the parts back together in the opposite order you took them apart, and start your engine to search for any smoke that gets out.