Thanks again old smokey.
I´m now really confident about the procedures and even more important is, that i know the background. That makes it easier to believe and understand.
Finally it is not so easy at all. You really need time to study through all relevant take off performance things. This topic is huge and there are a lot of books about it but you cant read them all. Finally you still have to work and dont want to spend all your spare time with tons of books giving you information on how things work but in the end there are even more new questions.
regards,
Leo