Don't do it both to one switch, if you do two different switches then you have double the security. Especially if they are both well hidden, any thief will think they are so smart when they find one, until the car doesn't start with it that hidden switch triggered. There have been a number of write-ups on this subject on the old forum. One of the best ideas I heard was to put a switch behind the ashtray. When you get out of the car, pull the tray out a bit to deactivate the switch, push it in fully when you want to start the car. Pretty brilliant if you ask me.