Jenson Button believes the gains found with McLaren's upgrades for the Malaysian Grand Prix were masked by the demands of the Sepang circuit.
Button and team-mate Kevin Magnussen both finished on the podium in the season-opening Australian Grand Prix, but were battling on the fringes of the top six in round two.
Group CEO Ron Dennis claimed beforehand that McLaren had brought upgrades worth half a second to Malaysia and Button said that he has faith in the team's developments.
"I don't think we're as competitive as we were at the first race, but I think that's just circuit dependent," said Button. "I feel that we've made a step with our car.
"We haven't done a back-to-back [test of the parts]. When you have such big parts, such big aero changes to the car, you can't just do back-to-backs.
"You waste too much time, so you've got to believe in the windtunnel.
"This year, so far everything that's come out of the windtunnel, the track has agreed with, which is great.
"I feel they [the Malaysia upgrades] have given us something, I think [Sepang] is a circuit where it's a bit difficult for us.
"The strengths of our car can't really show through.
"And the heat made those issues that we had even worse. I think with a cooler race, we'll have reasonable pace."
McLaren racing director Eric Boullier believes the Woking team has the right tools at its disposal to keep up in the development race.
"We are behind in terms of performance, but we know this and we are flat out on this," said Boullier.
"One of the big jobs over the winter was to make sure of the correlation between the windtunnel, CFD and the track.
"What we've seen since the Bahrain tests, Melbourne and here, every upgrade we brought is matching the numbers on track, which is a good sign and a good base.
"So we just need to keep developing and keep working. We have a further upgrade coming in Bahrain and I think every race we are going to bring something."