Take it as it is and ask for attention and advice on fuelling, take the advice and recommendations then go back another day. ive done this many times in the past with many cars and its always been the best way. not with rs turbos I must admit, still the power gains and results ive had from dyno runs and a well experienced bloke giving sound advise have been incredible. ive messed around loads over the years with guess work but good advise on the day has always been the best and quickest way.