You can actually fabricate this into the fire wall and hood of the vehicle and add a layer of sound dampener (cork material, or rubberized black matting) and it could be a fairly clean looking install and upgrade.

Same thing for building hardened enclosures (boxes) around some of the control electronic components (it might seem daunting, especially with modern cars, but there really aren't that many).

Also for EMP protection you can get an aluminum cable that reaches the actual ground and aluminum spike and ground the chassis to the ground itself. Functional cheap EMP protection. When the vehicle is not moving.

Works for generators too.