Was just stirring lol, of course they do. Weight is the first one that comes to mind for me, unless the car is weighed prior to a run it could never be 100% even if no other variables existed, which they do. What if I ate a sh*te load of KFC on the way. Or had weighed it on street rims and tyres but ran a diff set at the drags. Small differences but will effect accuracy none the less. Also a nice pic of willowbank I thought.