Tuning IS an art. You can read as many books as you want, but like you said, its trial and error. If you don't fiddle with it you will never learn. It's like reading a book about drag racing. Just reading a book won't get you the skills necessary to get a good launch or time. There is nothing to decrypt. All the info is out there, the rest you can figure it out if you dedicate some time.

I'm not saying anything about big name tunes, except that some are very conservative, and some need some work on some things. There is a few really bad ones, but they are from lesser names and I'm not going there. Just because you have a dyno and a team of 30 'engineers' in the room doesn't mean anything. Its like this in everything. You really have to want it. I do this because I like it, not for the money. The money just sweetens the deal