Carlos Sainz Jr is not expecting massive updates from Toro Rosso, revealing any changes will be "much smaller" after the big upgrade at the final test.
Toro Rosso made a solid start to this year's Championship with both Sainz and his team-mate Max Verstappen in the points.
The rookies have each scored six World Championship points to put the team seventh in the standings.
But whether they can hold onto that position – or even build on it – could depend on how the Faenza team copes with the development war, which is expected to get underway in erhnest this weekend in Spain.
Sainz, though, has revealed that his team won't be introducing any massive upgrades this season.
"We are obviously bringing some aero upgrades, but not a lot," he explained to Autosport.
"The biggest aero upgrade was obviously in test three in Barcelona.
"Now every upgrade will be much smaller."
Sainz is also counting on improvements from engine supplier Renault, saying that is what Toro Rosso most need to move forward.
"The biggest improvement that we need now is on the engine side," he said.
"We need to improve that, as it is the area where we gain the most performance."