WTF is it? And how does it come off?
 

Idiot alert.... WTF are the black metal housing(s) near the oil return tubes...? Pry them off? The move/wiggle but seem as it they are on springs. and, oh by the way... the Snap on collet stud remover does NOT fit the exhaust studs near the rocker assembly. I need input. Thanks fellahs

The black metal pieces are there to direct the air flow around the cylinders for better cooling

No, do not pry them off. There is a thin strip of spring steel that fits into a slot of the each piece of the cylinder cooling air deflectors on the top side of the cylinder.
Would be a good idea to pick up our hosts book on 1965-89 911 engines. It is full of great pictures and information on these engines, like this question.

I have those books and the air channels are not covered. Ergo - my questions. These Channels/Baffles are not covered in any of the three books I purchased. But - Thanks for your help. Any experience removing exhaust studs closest to the rocker arm assembly?

I hope the engineer who came up with Divilar is sitting in Hell ....

You could try double nutting them. They often break and a jig is needed to drill them out properly. If you do a search on exhaust studs I'm sure you will see it mentioned.
http://forums.pelicanparts.com/porsche-911-technical-forum/612080-removing-head-exhaust-studs.html

The cooling tins are definitely covered in Wayne's books.

If it's the tin around the cylinders, it's covered on page 33 of the How to rebuild and modify 911 engines, my book is from June 2010.

If you're talking about something else, post a picture, that might help someone help you.

Troll like