Just avoid problems by not flashing MS when you have the car running. Key on, motor not running. Not hard to do. When you flash MS there is a split second that the ecu has no program. It's just asking for headaches having the motor running at that time. If you are doing it at idle you might as well do it under full boost at 6000 rpms in 4th gear. Obviously a lot of people do it and get away with it. You haven't.