Supercars revealed on Tuesday analysis had determined the Mustang holds an aerodynamic edge over its Holden and Nissan rivals.

Led by DJR Team Penske star McLaughlin, the Mustang has won nine out of 10 races in 2019 and eight pole positions.

Its dominance has led to rivals claiming it has an unfair advantage and now the cars must undergo changes before next week's event in Perth, mainly to its rear wing.

"Nothing like fire in the belly," McLaughlin tweeted when the news of the enforced changes was made.

It's the second time this year the Mustang has been ordered to undergo changes after it and the Holden Commodore had to undergo centre of gravity changes in March when a test showed a disparity with Nissan's Altima.

Under Supercars regulations, changes are allowed if a significant disparity exists between the competing cars.

The continued revision of the Mustang's specification comes despite its initial specification being signed off in December by Supercars and the three teams responsible for vehicle parity - DJR Team Penske, Triple Eight and Kelly Racing.

"I guess now it will just feel a whole lot better when we win again #SaddleUp," McLaughlin added on his Facebook page.

Ford's global director of motorsport Mark Rushbrook was another to express disappointment in the changes.

"This is a world class car ... we stand by the state-of-the-art package we introduced into the series," Rushbrook said in a statement.

"From here on we will do our talking on the racetrack."

Australian Associated Press