There really is mate, and it's not just about changing values in box's or graphs either... it's understanding why you change the values and by how much to get the desired result, and knowing what the desired result is in the first place, then how those changes roll on and effect other values, and then the engine itself, and how changing pysical parts (cams, turbo's, etc..) then effect all of that to... seeing the whole picture mate!!
I've been researching/studying and asking tuners/mappers for the last year to learn as much as I have now, and thats probably only a very very small part of it... we are lucky we have such simple engines!!