On crossover, if your opponent is slower his top light will come on first and so on for the rest of the amber bulbs. On Crosstalk both top lights come on at the same time, then when its time the other amber come on just as the crossover mode. Now racing crossover mode and your the faster car, after you put in both dial-ins. You would have to look at you opponents top light on his side of the tree. If you running atrack with crosstalk mode and you where the faster car, after you put in both dial-ins, You would leave off your top bulb on your side of the tree. If your buying a delay box get the one with crosstalk it will work with both, and since most tracks are going to crosstalk mode. I like the Pro cube the best, but they're all pretty good anymore.