When I was playing Crysis 2, I was predominantly using Marshall and all the stealth mode. But in Crysis 3, one of the important suit modules that helped my Stealth play went missing. That module is no other than Energy Transfer. With that and Stealth Enhance and Mobility Enhance modules set me up for the ultimate combination of suit modules to go along with the Marshall. My K/Ds improved from a 1.4ish to 2.35 after that. Considering the fact that I already had a lot of deaths to begin with when I found this godly combination, that was a significant improvement.
With Energy Transfer, you could shoot while you were in stealth mode and kill someone and go straight into stealth mode back again because the energy was restored because of the kill. But you cannot do that anymore in Crysis 3. You have to either switch to stock mode or armor mode. Switching the suit mode quickly hasn’t been my strongest points. If you look at my Crysis 2 stats, even Crysis 3 stats (before a couple weeks ago), I’ve made most of my kills in Stealth mode. But with Crysis 3, my K/Ds are quite crappy. I’ve managed to get to 1.8, but it hovered around 1.5 mark for a long time.
After seeing a few YouTube videos, it seems the best combination is Scar Mod 2 for the weapon, Weapon Pro, Maneuverability and Rapid Fire modules. I use Reflex Sight and Extended Magazine as weapon attachments too. But the most important thing is, you should switch to armor mode before going up against an enemy, even if you shooting from behind – because you never know if someone else is close by to avenge his mate’s death. Armor mode will absorb a lot of damage, and with enough movements you can get away from enemy fire.