Unfortunately, as is often the case, when you undo the nuts holding the manifold to the head, it is normally the stud that comes out. Don't worry as they are fairly easy to put back in. For those of you who are experienced engine people, look away now
If you take a stud, place a nut on the manifold end, and then, holding that nut with a spanner, tighten another nut up against it.
And this will leave you with your stud looking like this
You can then tighten the stud back into the head. Do not overtighten as the head is aluminium and it can be easy to strip the threads.
To release the nuts, simply huld the inner nut with a spanner and loosen the outer nut. They should now both be easy to remove, leaving the stud in place.
The studs are now back in place and we can see the space where the manifold used to be.
Now fit the new gasget over the studs ready for the new manifold.
Now comes the easy part, yeah right, believe that and you believe anything. I spent at least 2 hours trying this way and that to get the new manifold in from the top. It will not go. I removed the alternator heatshield and bracket, I even removed the new alternator to give a little more room. Still no joy.
I then decided to go in from underneath the car. Nope. Oil filter was in the way. Banged my head against the ground. Nope, that didn't help either.
Bit the bullet and dumped the oil and removed the oil filter. This gave just enough room so that I could get the manifold jammed in a position I couldn't get it in or out. Banged my head a bit more.
Eventually I decided to use a lever against the oil filter housing to move the engine block back a little to give me more clearance. Before anyone tells me I shouldn't have levered there, I was moments away from removing the engine with my teeth, so it was the lesser of two weavils.
So, after a little gentle persuasion, the manifold was put in place and the nuts tightened. The alternator/heatshield was replaced and a new oil filter fitted.
And lastly the heatshield goes back on