The process is straight-forward: undo 16 nuts, pull manifolds away from engine, clean mating surfaces and reassemble. Undo an additional 4 nuts to separate the manifolds from the first cat to make cleaning the mating surfaces easier.
Now we can talk about reality…
- Steel studs chemically boded into aluminum heads
- Rusted nuts bonded to the other end of the studs
- Is there enough room to maneuver the manifolds after 6 studs are snapped off?
- Do you have a right-angle drill and proper tools to replace the stud holes in the head?
This thread dealt with it better than I can: