Exhaust manifolds often neednt be removed, but with full-length headers, theres no choice. Soak all the exhaust bolts with rust penetrant long before you begin. When youre unbolting the headers, take note of the bolts that go into the water jacket. Its best to put studs in those locations to ease future R&R, assuming the headers have room to slide on and off the studs. Also take note of the location of any specialized header bolts, such as those on 440 Mopar manifolds. Finally, keep in mind during engine removal that some headers capture suspension components and may not slide upward out of the car without some disassembly of the suspension.