I have a friend who has been foot brake bracket racing for almost 20 years. His average reaction time is .02. He won the heritage series in the 10.60 class a couple of years ago and he won all but one race. Typically he dials his car in to run 10.58-10.59 and lifts if he is ahead. he also runs 2 classes one with a .4 tree and the other with a .5 tree. He change front tires from small to big to get his reaction time for each class. In this old man's opinion delay boxes are for people who won't or can't practice enough to get their reactions consistant