For folks doing a new install and not wanting to run welding wire into the cockpit, take a look at http://www.cartekmotorsport.com/tech-info.html

I helped a friend put it into his Miata. The device sits between the battery ground and frame, and has a 2nd circuit to kill the fuel pump or ECU.

The trigger wires are small and you can run multiple. We put one near the driver and one outside for cornerworkers.