If the exhaust system fasteners are rusted or "frozen" you should apply penetrating oil to them and then just wait for a while before trying to undo them. Firstly, allow the cable touching the negative terminal of the battery to be disconnected. In addition, if used, the strut tower cross brace mounting nuts and brace should be also unbolted and set aside. For 4.0L models remove the EGR pipe from the left manifold and the EGR module. Lift the vehicle and securely stand it on jack stands and then remove the exhaust pipe from the manifold. Remove the bolts holding the exhaust manifold to the 
Cylinder Head and take off the exhaust manifold. Utilizing a scraper wipe down the mating surfaces on the cylinder head, manifold and exhaust pipe, eliminating the debris with brake cleaner. Make sure that the mating surfaces need not be scratched or warped; if they are, some of the manifolds may have to be machined. After removing the old gasket, allow the new gasket to be placed onto the cylinder head studs so that the manifold can be placed on the cylinder head with the bolts to be tightened to the recommended torque. Join the exhaust pipe to the manifold and fasten the nut at the same level of torque as recommended. The rest of the installation procedure is in the order of its reversal as pointed out in the steps of removal. Last and least, rev the engine and search for some exhausts sound.