Before attempting to loosen any exhaust system fastener, apply penetrating oil to the fastener and allow it to soak in for a while. Replace damaged fasteners with new ones. For 2005 and earlier models, the primary catalytic converters are bolted to the undersides of the exhaust manifolds. Begin by raising the vehicle and supporting it securely on jackstands. Unbolt the exhaust pipe from the bottom of the catalytic converter, then disconnect the rubber exhaust pipe supports under the vehicle and carefully lower the front of the pipe for access to the catalytic converters. Disconnect the oxygen sensor electrical connector, unbolt the converter from the exhaust manifold, and remove it from beneath the vehicle. Installation is the reverse of removal; ensure new gaskets are used, apply anti-seize compound to the threads of the fasteners, and tighten them securely. For 2006 and later models, the primary catalytic converters are integral parts of the exhaust manifolds. To address the secondary catalytic converter, raise the vehicle and support it securely on jackstands. Remove the fasteners from the flanges at each end of the catalytic converter, push the converter to the rear to detach it from the front portion of the exhaust system, then lower the front of the converter and detach it from the rear portion of the exhaust system. Installation is the reverse of removal; again, ensure new gaskets are used, apply anti-seize compound to the threads of the fasteners, and tighten them securely.