Quote, originally posted by Woodljp » ...do you have to remove that big magnesium air chamber thing to get to the plugs?
Only the two sides of the intake manifold, not the center portion. See this thread for illustrations and pictures that will give you a bit of a perspective on how it is done: F265 Map Controlled Engine Thermostat Replacement.
The photos there show the middle section of the intake manifold being removed and the two side sections (throttle bodies) being left in place, what you want to do is exactly the opposite - remove the two side sections and leave the middle in place.
In practice, though, it is easiest to remove the whole assembly (two side sections and the middle section). Be sure to put some tape over the holes leading to the intake valves - otherwise, you will be in a world of hurt if something falls down one of those holes.
Be darn careful when handling those parts - the three parts (two throttle bodies and middle piece) are hand-tooled to match each other, and have to be replaced as a set. The price for a set is a five-figure number.