When your at a part when 3 men are guarding the second valve and every time you go up they see you and shoot you here's what to do when a man with a gun comes up to the end of the room near you don't jump up they'll shoot eventualy the man will turn around and walk away but when he turnes around jump up and stealth attack him then role over to the second valve and activate it the other men will drop there guns beat them up

To unlock all bat suites:
Beat the game

To unlock both batmobile missions:
Beat the game