Sebastien Bourdais is hoping that Scuderia Toro Rosso makes a big step forward in understanding the setup requirements of the STR4 this weekend.
The Frenchman, who has scored two points so far this season, was unhappy with the team's pace when it upgraded the car at the Spanish Grand Prix.
"We're just trying to understand what we need to do to get the car working," said Bourdais. "Barcelona was a big disappointment for us – we didn't produce better performance. But saying that, we know on the pure downforce side that the car has made a big step forward."
Bourdais said that he was frustrated at being so far behind sister team Red Bull Racing.
In Spain, the car was upgraded to the specification that Red Bull started the season with, and despite potentially being a big step forward, the Faenza-based team is still a long way off them.
"We've got a lot closer to Red Bull than we've ever been, and yet we're still as far as we've ever been," said Bourdais.
"We are not satisfied with that we were have spent a lot of time trying to understand what the setup has to be to use the car in the best way. I hope we've done that.
Bourdais added that the team has introduced some minor aerodynamic upgrades for the Turkish Grand Prix.
"A few things, just like everybody else," said Bourdais. "Nothing major. Some flaps and stuff."