Daniel Ricciardo says Red Bull expects a power unit upgrade from Renault around the Canadian Grand Prix, round seven of the 2016 Formula 1 season.
Renault believed it found half a second per lap with updates it ran at testing and made further improvements ahead of the season-opening Australian GP.
When asked by Autosport if he felt like there was more performance from the TAG Heuer-badged unit, Ricciardo said: "I do, but we're not talking a massive step yet.
"When you've already got x-hundred amount of horsepower and you get five or 10 extra horsepower, it's not a world of difference.
"You don't really feel an extra kick when you put your foot down.
"But I do feel like sort of top end, at the end of the straight, it just seems to run more, so it has a bit more legs in the last quarter of the straight.
"Once we get to - at the moment we're talking sort of Montreal - we should have a proper step.
"And then hopefully I get some whiplash and some good g-forces through my neck!"
Red Bull team principal Christian Horner agreed that progress had been made by Renault, particularly in race trim.
"The power unit has definitely made progress over the winter," he said.
"There is still a long way to go but it's great that, particularly in race conditions which is what we saw in testing, there has been progress in performance.
"Hopefully the guys will take back a lot of encouragement that they're going in the right direction."