I just wanted to point out (if someone haven't already done so) that Webber and Vettel were running different exhaust systems.
Source: http://www.formula1.com/news/technical/
Here is a quote from one of the articles:
Source: http://www.formula1.com/news/technical/
Here is a quote from one of the articles:
The two Red Bull drivers qualified with different exhaust set-ups in China. Whilst Sebastian Vettel opted to run a solution used in pre-season testing with the exits further inboard, directing the hot air towards the beam wing, Mark Webber used the newer layout which the team ran at the opening two rounds of 2012. On this solution the exits (two variations shown here, the left one being used in Shanghai) are further outboard and direct the hot air towards the outside of the car, close to the tyres and the rear diffuser's side channels.