Tony, thanks- I thought I had the latest update but will give that a try. Matt C- you do not need to have GPS for the predictive-used it long before I bought the GPS. Look at the manual for the Mychron 4, it explains the setting needed to get it to work off the beacon. When I say I switched off the GPS, I mean I physically took the unit off the kart-not just switched a setting. Hopefully the firmware update will allow me to use the predictive with the GPS as our track tends to forget to keep the beacon working from time to time.