To those who are experiencing turbo going missing after a few laps, check your esc temp. Does it happen when it reaches 3 leds? Mine does.
However, Randy have insisted that the esc temp does not affect turbo. He suggested recalibrating the esc with 95% epa on throttle forward, and then setting back to 100% afterwards. I haven't tried it yet but hopefully it works. It is so annoying being fast only for a couple of minutes!