Ferrari has reportedly found 15 horsepower to add to its 2020 engine ahead of the resumption of racing in Austria early next month.
Ralf Bach, a prominent German journalist writing for Sport1, said the update is also more reliable following problems with the Melbourne-spec engine in winter testing.
As for the power upgrade, Ferrari's engine was clearly superior in 2019 but it suffered a clear performance drop amid an FIA probe into its legality.
"Ferrari's power unit was much stronger last year," Mercedes team boss Toto Wolff is quoted as saying.
However, he said it is too early to conclude that the same weakness would still have been seen if qualifying and the grand prix had gone ahead in Australia.
"Only in qualifying and in the race does everyone show their true strength, and we haven't been there yet," Wolff added.
"But I also would not dismiss Honda and Renault. My feeling is that pretty much all of the engine manufacturers are at eye level now."
Bach wrote that Ferrari has also tweaked the design of its 2020 transmission ahead of Austria, but that major aerodynamic upgrades will only be seen later.
