Designing the suit was fun. I found some old Roller Blades in a pawnshop which had a nice rubbery/leathery sound when it got twisted, which was used to create the suits foley sounds. The Armor boots sounds are designed from the same source.
The suit switch armor mode, was designed from cracks, like cracking ice for example. Filtering, compression on different elements that impacted the suit (armor mode) was applied switching the modes. So environmental audio got either enhanced or frequencies cut (stealth mode).