The ballast should be given for championship position, not finishing position.
Take this round as an example of why it doesn't work:
At Fe Gold Rev the RAC's have a 1 second a lap advantage and thus only RACs get a weight penalty.
The next event is Aston National Rev, where FZ5s have a 1 second a lap advantage, but no FZ5s have a weight penalty.
This doesn't help to bunch up the field, actually it even stretches it further apart because the top FZ5s pull away from the average RAC-drivers at even more than 1 second a lap and the top RACs have the weight penalty.
You could at least make the championship closer by awarding the weight penalties for the topmost championship positions. That way the championship leader can't increase his lead at the same pace anymore.
Vain