Sparky,

21% pot return is a very good figure [exceptional] for backing 4 horses per race based on ratings. Boy, who's are those?

What is your average winning odds to reach that sort of figure? It would have to be quite high as even at $8 units win average your true odds for 4 runners is only evens. $4w would be money back and no profit. 68% SR is a hint I suppose but I can't figure it at the moment [I've got the flu]. Maybe someone here can[?]