Its actually pretty simple, it is the first system I ever try to tune my self and it came out pretty decent. it determines the amount of fuel to add/remove depending on Boost and RPM. there is a base map for the MKIII on the map ecu website. read the manual and read it again. and I am assuming you have wideband otherwise go get one right now. once you load the software and you look at it for few minutes it should all come together.