Stupid question but I'll ask anyways.... I trying to diagnose wether its my booster thats out since my brakes are harder than hard to stop. So when I get a vacuum gauge do I just plug it into the line that goes into the manifold? And once I do that I just start the car up and check the vacuum? And what the required suction, I heard 12 inches I think its inches? Please help me out.... Maybe stupid questions but I'm hear to learn. Thanks