When carrying out the step that involves the removal of the exhaust manifold, it is advisable to disconnect the cable from the negative terminal of the battery. Then, elevate the vehicle and position it on jackstands firmly. Remove the exhaust pipe from the exhaust manifold, if the nuts are rusted, use penetrating oil to allow the nuts to be turned Lifting the car. Subsequently, pull the exhaust manifold heat shield and take off the large air hose of the air switching valve. Depower the air switching valve then take out two nuts on each end of the air tube along with their gaskets and properly remove the air tube before the removal of the mounting bolts of the air switching valve. Pull the vacuum hose and wiring off the air switching valve, then take the valve and gasket away. Soak the eight exhaust manifold mounting nuts with penetrating oil and wait a little before removing them to loosen the manifold and the gasket. For installation, the surfaces of the manifold and 
Cylinder Head should be scraped free of any old gasket material and carbon build up. If there was a problem with gasket, then the manifold should be examined for warping and if it is, then it should be resurfaced. Place a new gasket over the cylinder head studs, place the manifold and do up the nuts on the studs. Incrementally tighten the nuts starting from centre and moving outwards or turning the nuts in three or four turns with equal force to reach the required torque. Lastly, replace the remaining components in reverse and start the engine and check for exhaust leaks.