Check the Location, Location, Location section in Run&Gun for rules on the exact effects. Remember, Shadowrun doesn't do the whole hit-location thing really. A piece of armor that has armored legs added to them raises your armor in general, not only when your legs are targeted. The same for Helmets, knee-protectors, shirts, gloves, etc. Inside combat it doesn't go aside from what's in the rules, outside combats you can torture people all you like.