Is this car for use on public highways and roads? If so, I'd expect your insurance costs to go up with this modification, both due to reduced security and increased risk of something going wrong.
Do you know what you are doing enough to make this 100% reliable circuit? If it turns off the ignition when you are driving at 60mph, you are in big trouble. Bear in mind that on modern cars, power assisted steering and power assisted brakes require the ignition to be on to function.
This sounds like a dangerous project for a beginner, and I'd imagine people will be reluctant to help.
Andrew