It was a cagey first half with both flyhalves trading penalties leaving the score at 9-6 to the Stormers with no clear dominant side.
However, the Stormers picked up the intensity and took control of the match, outclassing the Bulls in all areas of the game.
They scored three second half tries with du Preez, Scarra Ntubeni and Eben Etzebeth the scorers on their way to earning themselves a bonus point.
Du Preez scored the first try adding to his superb kicking performance, he scored after finding himself out wide forcing his way over after the tryline after Stormers had assaulted the Bulls defensive line.
