Have used the programmer many times on planes to increase the trravel, have only used it to reduce the travel on surface vehicles. That way you get to make better use of the resolution of the radio on surface vehicles. What are you using it on that would need increased servo travel?
I can tell you this up front, read and understand the instructions before you start. It's not hard at all, but if you jump in not having a clue you will wind up with useless servo's if you don't know at least how to return them to factory settings.