Battery cut off switch

Talked to the fellow at Mad Electrical about this a while back. My concern was having electronics, namely a EFI brain and a trans controller. Mark (?) told me that no matter how you wire this there is a VERY good chance of an electrical spike when the battery switch is tripped. The reason for this is the alternator, for a very brief amount of time will still be putting out current. This current will have no place to go but directly into your electronics. He suggested that the field wire be ran to a separate disconnect switch, something tucked away inside the car someplace. Once you are heading to tech inspection or the staging lanes the field switch should be triggered, disconnecting the field circuit in the alternator, disabling it. At this point, the car will effectively not have an alternator.