If the shock sensor is part of main control module the best place to mount it is the steering column. If the shock sensor is separate, the column is still a great spot. If you have no room there, centered up high on the fire fall is the next best spot. Never mount the main module on the outside of the car. Near the fuse box and steering column is where all the wires are that you will need to tap into. Run your “solenoid” wires {I’m assuming these are for the doors} to that general location and wire the whole thing at once. This will help you avoid making unnecessary splice after splice each time you add a new alarm component. All of your power needs should come from the column; they are all there- constent, switched, crank, horn & ground. Your light flash wire can be accessed from the back of the headlight switch.