The Hinwil-based outfit has yet to score points this season with the pack seemingly split between the top five and bottom five teams, though Haas and RB have breached the top 10.
Whilst Zhou Guanyu and Valtteri Bottas have shown glimpses of form behind the wheel, their efforts have largely been hampered by persistent issues at pitstops linked to new equipment introduced over the winter.
With wheelnuts becoming cross-threaded during stops, both drivers have been left languishing at the back of the field after changing tyres, though both escaped delay at the Miami Grand Prix.
After a pitstop that took over 30 seconds and saw Sauber fined for an escaped wheelnut entering the fast lane at the Australian Grand Prix, Bottas revealed the team had apologised for the issues and added: "We’re in this together.
“I was disappointed, but the whole team was disappointed because these things shouldn’t happen.
“So, we’re definitely taking it seriously and it is a priority now to get that sorted.”
But around the Hard Rock Stadium, Sauber didn't have the performance to trouble its rivals despite escaping any issues in the pits, even with Zhou attacking after a safety car period on a set of soft tyres.
"I think that the strategy to put soft was correct one, we didn't have tyre degradation," said Alunni Bravi.
"He was able to score his fastest lap at the end. But we were struggling for most of the race behind [Alex] Albon - also with the DRS to not be overtaken, benefiting from a better top speed than us.
"So we tried everything in terms of strategy, in terms of tyre compounds, but simply it didn't pay. Again, we need to bring upgrades, we need to do an extra step in the performance, because what's been done so far, it's not sufficient.
On the changes that will be made, Alunni Bravi explained: "We have important upgrades in Imola. Not only concerning our pitstop because we will have all the new parts to ultimately fix the problem with pitstops.
"Then we will have an important upgrade coming in Imola. So I think that this will determine the next three-four races and the possibility for us to score points or not."
