I’m decarbing the intake this weekend. I’m not finding a clear way to rotate the cam to ensure closed valves as I progress through the cylinders. Some say turn the alternator but that may throw off the timing. Is this correct? What’s the best method?

Hi - I was looking at removing the intake and cleaning the valves on a 2007 Golf 2.0 FSI.

I then saw something on HHO Decarbonisation that claims to clean the carbon off everything in the engine including the valves.

Has anyone tried this ? What were the results ?