McLaren has elected to continue with its new blown diffuser into Saturday after testing the part during Friday practice for the German Grand Prix.
The team had hoped to run the part at Silverstone a fortnight ago before issues in practice forced McLaren to abandon those plans, with the team then working on improving the parts ahead of this weekend's race.
Despite limited track time for Lewis Hamilton on Friday after his accident in the opening session, McLaren has now elected to continue with the part for qualifying later today and Sunday's race in the hope of taking the fight to Red Bull.
"Based on the data, we will be running it," Whitmarsh told Reuters
. "The data that I saw from P1, albeit wet, was that the main vehicle airflow, the gas flow from the exhaust, temperatures, the performance and pressure tapping velocities were what we expected them to be.
"So unless something else has come to fruition, which I don't think it has, then we should have the confidence that this floor will do either everything we expect it to or most of what we expect it to."
McLaren currently leads Red Bull in the title race, despite its rivals having the quicker car in recent races.