It was only back in Monaco that Red Bull introduced its revised package aimed to benefit from a new double decker diffuser, and now again the RB5 is fitted with an update. The element is possibly as good an improvement as the original DDD was.
This time around the new diffuser now spans the maximum width, while previously the team, along with Toro Rosso, was the only not to use this. All diffusers of the RB5 in the first 7 races were the width of the rear wing, with its endplate extending down to form the diffuser walls. Although now they are still attached, the endplates only reach onto the diffuser, not down to the reference place.
Also note the added hot air exhaust in the engine cover to cool the car's internals better.