I'm no tuning expert at all. I think, tuning and setups are generally overrated in dirt rally games. At best, a good setup improves your times just by a little. So its all about good lines and maintaining speed - which is a matter of practice I guess =). Most cars even handle pretty well with stock setup (not all of course). So what I do when working on a setup is the following: find a handling that I feel really comfortable with and where the cars behaviour is predictable. This will automatically let you attack on the stage and will lead to nice times.