The French engine manufacturer had been forced to adopt more conservative settings in Australia and Malaysia due to reliability concerns, but Taffin says they are now in a position to be more aggressive in Shanghai, where top speed has an increased importance due to the long straights.
"In Malaysia we got close to what we would consider the normal level of driveability we had at the end of 2014," Taffin said.
"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."
Taffin said that as a result both Toro Rosso and Red Bull should make a competitive step forward this weekend.
"We finished in 7th, 8th, 9th and 10th in Malaysia and with the improvements put in place we hope to be further up," he added.
"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."