As the cars completed all the testing that is allowed, the crew on track and at the factory have been practicing pitstops without refuelling the car. While previously the tyre changers were not the critical path of a pitstop procedure due to the longer refuelling time, they certainly will be now.
Williams have stated a 3.5s stop will be "decent", but rumours from Red Bull claims pitstops of under 3 seconds. To optimise this process, most of the experienced teams have designed special wheel nuts that can unlock the wheel safety fastener and the wheel at one time. Ferrari did it by adding two clips on each side of the nut.
Many will surely be eager to find out the car's relative performances at Bahrain, but the teams' pitstops will be at least as interesting.