Interesting read mate, cheers for the link!
I used carb cleaner from tool station for mine, bought 2 cans for a fiver and still got half one left. It is so strong it melted the plastic handle on my wire brush, so make sure you remove the rubber gasket from egr before using it. Due to this I didnt use it for the manifold as its plastic also. I only used gunk degreaser which wasn't really powerful enough as you can't get inside with a brush unless you use a pipe cleaner or something. Most people on you tube use Mr muscle and a pressure washer with great results, unfortunately I didn't have any as I hadn't actually planned to do the manifold, but when realised how easy it came off I though might as well.