All three Supercars models will undergo a new ballast distribution change ahead of the next round in Queensland, as part of the category's ongoing parity adjustments.
Both the Ford Mustang and Holden Commodore were handed mandatory ballast redistributions at the height of this season's fierce parity debate and teams were forced to move additional weight to the roofline.
A total of 28kg of ballast was clamped to the top of the roll cage in the Mustang, while the Commodores had 6.8kg fitted to the panel immediately behind the windscreen.
Supercars has now updated the ballast ruling following the second round of centre of gravity tests.
Ford teams will be able to redistribute 9kg of ballast from the roofline of the Mustang but composite materials will have to make way for steel beams in the roof.
The Holden teams will be able to redistribute all of the roof weight that was added in that earlier change, while the Nissan Altima - unaffected by the first ballast ruling - can shift its existing engine ballast to the sump.
The ruling only affects the positioning of the ballast and not the overall minimum weight of the cars.
"The Commission approved the change following further work into the positioning of ballast through a more refined process using CAD," said Supercars head of motorsport Adrian Burgess. "
With some teams not returning to their base between Darwin and Townsville, we decided to implement the change for Ipswich after all teams have had time in their own race shops.
"The repositioning maintains the current balance between all makes and has an equal effect on performance for all."