As harstad indicated kidnappings are not something the general public is really worried about, but carjacking occur frequently and while they are not as well trained they can use the same type of violence. Chances are if you’re in an area that is prone to this kind of violence your choices are going to be extremely limited. I’m not sure how you would explain to the police about the armor let alone the electrified panels and flame throwers. I can’t think of any thing that would be 100% legal in all states. So all I can say is you will have to defend yourself as best as you are able and willing to.