Just to add to PalmettoDisco's note--the best socket to take them off is a 5/8 rough impact socket. Smooth sockets tend to slip. Also, those SAI plugs are going to be in the way unless you use some clever wobble extensions on your socket.

 

Charlie, thanks. I we used the 5/8 impact socket. Those were tough to get out especially the those at the back of the engine. We took our time with those thinking we might end up stripping the heads.

 

The back ones are hell. After doing it a few times, I use wobble extensions and get far away from them (like, a couple of feet of extensions). Putting the bolts on is a little easier than getting them off, for some reason.

You'll want to be sure to clean the threads/holes out; coolant and oil gets in them when you pull the heads.

The whole job is a PITA!