McLaren's 'F-duct' air inlet and rear wing system is working well on the long straights of Malaysia's Sepang circuit.
Lewis Hamilton was quickest in both practice sessions on Friday, helped in no small part by a sizeable straight-line speed advantage.
"It's quite a high downforce circuit and I have no doubts the Red Bulls and Ferraris will have more downforce in their cars than us," said the Briton.
"But hopefully we will be able to balance that out with our straightline speed."
Part of McLaren's advantage is the lack of downforce and the impressive Mercedes engine, but also working well is the F-duct, where Hamilton and Jenson Button block an inlet with their left knee and stall the efficiency of the rear wing.
"Our straightline speed is really good," admitted Button. "We were 14kph quicker than the Red Bulls (on Friday). 14!" he enthused.
Also helping McLaren at Sepang on Friday was the anonymous performance of the Ferraris, and also the fact that the dominance in Australia and Bahrain of Red Bull's RB6 might not have carried over to Malaysia.
"We are not at the same level as in the last two races," Sebastian Vettel is quoted as saying by Spain's El Pais. "We need something extra in order to be on the pole.
Red Bull's motor sport advisor Helmut Marko told sport1.de: "You're right, in sector two we're better but in sectors one and three with the long straights we are lacking top speed.
"We want to win the championship, so we can't say our car is good here and not good there. We must have a car that is good everywhere," added the Austrian.