While Renault says the driveability of its power unit has improved significantly since the first race of the season, Taffin admits the engine has not been run at full performance yet in order to protect reliability.

With reliability issues now under control, Taffin says Renault can afford to push the limits and get higher top speeds.

"In Malaysia we got close to what we would consider the normal level of driveability we had at the end of 2014," said Taffin. "For China we will have some small steps forward.

"We have continued the intensive test program started after Australia and we will see further results in Shanghai.

"Performance was likewise an improvement in Malaysia, although we did keep some in reserve to safeguard reliability.

"Now we are getting more confident in this area we can afford to be more aggressive and we should see better results on the straights, with a higher top speed."

Red Bull & Toro Rosso target Williams

Taffin believes the improvements should allow Red Bull and Toro Rosso to fight with Williams this weekend.

"We finished in seventh, eighth, ninth and 10th in Malaysia and with the improvements put in place we hope to be further up," he said.

"Toro Rosso has shown it has a good basic car and the drivers are confident, while Red Bull should be on top of the issues experienced in Malaysia.

"With the improvements to driveability and overall performance, we hope we can fight the Williams' cars and grab some more points in China."