Sebastian Vettel found the Red Bull RB8 more comfortable to drive during Friday practice for the Chinese Grand Prix after switching to the exhaust design used during preseason testing.
The double world champion ran the old package to allow the team to conduct a comparison with the latest specification used by teammate Mark Webber, but is unsure whether or not he would continue with the car in this configuration.
"I think I felt a bit more comfortable here today and a bit more together, so we will see," said Vettel after practice. "It's a bit tricky now to say. I don't have the [point of] comparison on this track, and it is cooler here, but it looks a bit more competitive and looks fairly close.
"I don't know [if we will keep the exhaust on the car] but for now I am pretty happy. Now we need to look at the data and compare the two cars to see which is the best package to come up with."
Webber was also happy with the progress made during Friday running and is hopeful that analysis of the comparative data of the two cars will allow the team to make a step forward on Saturday.
"I haven't driven the car for a while that Seb had today, and neither has he," said Webber. "It's the first time he has been back in it and there are changes and differences on how the cars work on different parts of the lap, so we need to go through it tonight.
"We might rob a little bit of each other's strengths and weaknesses. In general, we are going in the right direction."
Vettel and Webber ended the afternoon practice session third and fourth fastest, 0.172s and 0.460s off pacesetter Michael Schumacher respectively.