When you deliver more than you promise people are pleasantly surprised. It’s like a waiter at a restaurant who delivers outstanding service, and you want to tip him because you are thrilled and surprised that they did so well. So the notion is, if you promise to do X, deliver 5X or 10X and people will be touched and impressed and they will think that you are differentiated from the pack, which is exactly what you want. So dazzle them and deliver more than you promise.