The Nissan cars stay as is, the Holden Commodore ZB's have to add 6.7kg to the roll cage under the roof and the Mustangs have to add 28kg.
Add in a virus that the 25-year-old was battling, and the win had more significance than potentially expected at the start of the week for McLaughlin.
"Great job to get a one-two, awesome," said McLaughlin, coughing post-race.
"I'll have a good sleep, watch a bit of the footy and try and come back stronger.
"We've worked hard behind the scenes. There's been a lot of stuff thrown at us, but we just fight on. We're a strong group."
McLaughlin, who qualified in second, beat polesitter Winterbottom off the line, then edged away to lead by a second after 10 laps.
The Shell Mustang had doubled that advantage by the time pitstops started nearing the halfway mark, and he maintained that buffer over teammate Coulthard for the rest of the race, to claim his 31st victory of his career.
It was Coulthard's second podium of the season, while van Gisbergen made the most of a decision to pit late to pass David Reynolds, James Courtney and Winterbottom to earn third place.
The other New Zealanders in the race had solid rides, with Richie Stanaway finishing in 16th, while Andre Heimgartner moved up seven spots from his qualifying position to finish 18th.
In the overall standings, Coulthard now sits third, just seven points behind Mostert, while van Gisbergen has jumped into eighth after a poor start to the season.
The eighth race of the Championship is held tomorrow afternoon.