Like I mentioned before, when you remove the figure straight out of the box, he looks like this - no neck with shoulders all hunched up.
Removing the helmet/head, chest plate armor and neck sleeve, you can access the rubber bands joining the shoulder armor which are twisted too tightly, causing the shoulder armor to hunch upwards. Releasing them gives the shoulders more room and looks better
The new and improved look of Sideshow's Imperial Stormtrooper. Like I said in the previous post, don't push the helmet in all the way so that he looks like he has a neck.
Pictures of Sideshow Imperial Stormtroopers with Darth Vader here