The performance of the Ford GT has been pegged back ahead of the test day for the Le Mans 24 Hours at the start of next month.
Ford, which won the GTE Pro class at Le Mans last year, has received a double hit in the pre-test Balance of Performance, while rivals Aston Martin and Chevrolet have been given performance breaks.
The Ford will run at the test on June 4 at 1268kg, 20kg up on the weight at which it raced last year, and has also had its power reduced with a revised turbo boost curve.
The Aston Martin Vantage GTE will be 10kg heavier than last year, but has been handed a 0.8mm increase in the diameter of its engine air-restrictor.
The Chevrolet Corvette C7.R has received a 0.7mm increase in restrictor diameter.
Ferrari's 488 GTE, which finished second in class last year with Risi Competizione, is unchanged, because it is the car that the rule makers have chosen to balance the other competitors against.
The new mid-engined Porsche 911 RSR, which will be racing at Le Mans for the first time on June 17-18, will run at 1258kg and with a 30.1mm restrictor at the test.
Le Mans 24 Hours organiser the Automobile Club de l'Ouest and the FIA have reserved the right to make further changes before and during race week.
John Gaw, managing director of motorsport at Aston Martin's Prodrive team, told Autosport: "We've got the BoP and we are happy with the process that the FIA and the ACO have taken.
"We are confident that it will be correct on race day."
The BoP for Le Mans this year is not part of the automatic system introduced for the rest of the World Endurance Championship.
The performance of the cars is adjusted for the six-hour races, starting at the Nurburgring in July, according to a new logarithm into which data from the previous races is fed.
Le Mans is treated as a special case courtesy of the unique demands of the 8.47-mile Circuit de la Sarthe.
The 10kW power hike, equivalent to 13.5bhp, for all GTE Pro cars introduced at the start of the 2017 WEC season, has been removed for Le Mans as part of the balancing process.