On some models, the catalytic converter is integral with the exhaust manifold, requiring replacement as a unit. The 1.5L and 2.0L models do not utilize a separate exhaust manifold, as it is partially cast into the 
Cylinder Head, with the turbocharger mounting directly to it. To begin removal, raise the vehicle and secure it on jackstands. After the engine has cooled, soak the manifold heat-shield retaining nuts with penetrating oil to loosen any rust, then remove the heat shield and apply penetrating oil to the exhaust manifold mounting bolts. For 1.6L engines, remove the turbocharger, while for 2.3L and 2.5L engines, disconnect the exhaust pipe from the exhaust manifold and discard the old flange gasket. Unplug the electrical connector for the oxygen sensor and remove it from the exhaust manifold. Next, remove the exhaust manifold mounting nuts, then take off the exhaust manifold along with the old manifold gasket. Use a stud removal tool or two nuts tightened against each other to extract the old studs from the cylinder head. Inspect the exhaust manifold for cracks or damage, replacing it if necessary. Remove all traces of gasket material from the mating surfaces with care to avoid scratching, and inspect for wear and cracks. Check the exhaust manifold mating surface for warpage using a straightedge and feeler gauge, and determine if replacement or resurfacing is needed. For installation, place new exhaust studs in the cylinder head, install the manifold with a new gasket and self-locking nuts, coating the threads of the exhaust manifold studs with anti-seize compound. Tighten the nuts in several stages, working from the center out, and complete the installation in reverse order of removal. Finally, run the engine and check for exhaust leaks.