Let's be practical. You think you could hear a beeper on your radio at a RC car race over the noise of 10 engines? Maybe, but at the typical club race setting, either your pitman will tell you to come in, or the race announcer will be calling time for popular (ie., multiples of 5 or 7.5 minutes) fueling windows. Also, if you're not prepared like that or you can't hear a thing the announcer says the next best thing is to come in about when the other drivers come in. No, I don't have a 3PJS.