Red Bull are planning to make the next big step with their chassis at their own Austrian Grand Prix in July.
The former champions closed the gap to Mercedes and Ferrari with a significant upgrade in Barcelona.
Boss Christian Horner said that Red Bull will now assess the next move, after earlier problems arose with correlation between CFD, the wind tunnel and the track.
"We are looking at which of our tools we can rely on and which we cannot," he told Auto Motor und Sport. "The wider tyres have a greater impact on aero than we thought."
Red Bull do now at least have the full attention of Adrian Newey, after the famous F1 designer spent much of his time in the last two years on non-F1 projects.
Indeed, Newey was even in Barcelona.
"Adrian wanted the feedback from the drivers to better understand the car and determine the direction for the future," said Horner.
There will be only minor upgrades for Monaco, while a special low downforce package will debut in Canada.
However, a big upgrade is due for Austria, the race promoted and hosted by Red Bull. The team are hoping that a better Renault engine is also available by then.
"If we could turn the power up full, we would not be far from Mercedes and Ferrari," an unnamed team member said. "But because of reliability, we can't do it yet."
Red Bull are currently on 72 points to second-placed Ferrari's 153.