Despite being able to push "a bit harder" with their engines, Pat Fry has downplayed Ferrari's Montreal updates.
Fernando Alonso set the pace in the morning's session at the Circuit Gilles Villeneuve, crossing the line 0.016s faster than Lewis Hamilton.
And although the Mercedes driver was quickest in the afternoon, the two Ferraris finished fourth and fifth with Kimi Raikkonen ahead of Alonso.
The duo were both half a second down on the leading Mercedes driver, an improvement on their recent form.
Explaining the updates that Ferrari brought to Montreal, Pat Fry told Autosport: "There were quite a few bits, aero, control system tuning, obviously the engine reliability updates, which allowed us to push the engine a bit harder as well.
"It's far too early to be able to say if it is working or not - we need to look at more detail as normal.
"We need to keep developing the car as quick as we can."
However, the head of engineering at Ferrari admitted that catching the Mercedes drivers this weekend may be a step too far.
"I think that will be a very tough challenge," he said. "There is quite a gap to close."