A Kill Switch is Effective if you DIY , That way only you know where it is , and Anyone else will have to find it , Most Crooks will not even suspect a Kill Switch in the First Place so it's always a Good Idea , Use the Switch as a Supplement to your Existing Security System , The More the Merrier , Check the DIY Section for the A - Z of how to install a Kill Switch , Its an Easy thing to do for Extra Security. When you Send your Car for Service , Keep the Switch on So that even the Foreman Wont know its there.