Always go by the catalytic probe temps, I have a thermocouple on my liner just so I can see from across the room if I need to increase/decrease the air on mine or reload, I know that if my exhaust temp is about 400 I need to decrease the air and if it is around 180 I need to reload, but I always double check my probe before doing so.
Don't pay much mind to the magnetic thermometers.
Don't pay much mind to the magnetic thermometers.