"We brought some stuff before, but it was not particularly big, so this one is a bigger one and it is a very important weekend," said the series leader and three-time world champion who seeks to complete a Hungarian hat-trick this weekend.
"I think for everyone, this is an important, important weekend."
The 26-year-old explained that he felt the team needed to step up the pace to boost their defence of both the drivers' and constructors' titles.
"You could say that," the Dutch driver said.
"I think so. If this is not giving us some good lap time, I don't know how the rest of the season is going to evolve, but at the same time, I also don't know what's coming from the other teams.
"So we just focus on ourselves. We are bringing some things to the car and of course, I hope that it will give us a bit of lap time."
For his Red Bull team-mate Sergio Perez, this is another key weekend to prove he can recover his form and deliver podium finishes.
While Red Bull fitted upgrades to their cars, McLaren were forced to close their 'Team Hub' multi-storey motor home in the paddock following a storm on Wednesday.
The facility was left flooded in places only weeks after it was damaged at the Spanish Grand Prix by an electrical fire.
"The team are currently working to fix the damage and therefore unfortunately our Team Hub will not be open to any guests or media for the duration of the Hungarian GP," said a team statement.
In Spain and Austria, when the facility was out of action, team chief Zak Brown used the FIA's hospitality area as his base while drivers Lando Norris and Oscar Piastri used other McLaren facilities.
English driver Norris arrived in the paddock on Thursday to be greeted by light-hearted references to the European Championship soccer final which he attended in Berlin last Sunday.
A message on his car parking space board read '2-1 Viva Espana' in reference to Spain's Euro 2024 final win over England.
Two-time champion Fernando Alonso of Aston Martin told reporters he was not responsible, pointing out "there is another Spaniard" before it was revealed that the joke was the work of Carlos Sainz's manager Carlos Onoro.