Porsche’s quest for a fifth consecutive win in GT Le Mans next weekend at Circuit of The Americas has been made tougher, following the release of the final round of Balance of Performance adjustments for the GT cars on Thursday.

The Porsche 911 RSR has been given a 20kg minimum weight increase for the final two TUDOR United SportsCar Championship rounds of the season.

No other adjustments have been made in the GTLM class, although the GTD-spec Viper GT3-R has been given a 15kg weight increase and 3mm larger air restrictor, bringing the Viper back to pre-VIR power levels.

The changes come in the wake of a bulletin issued by IMSA on Wednesday, confirming a change in the Supplementary Regulations allowing for one additional BoP adjustment to be made this season.

IMSA had previously reached the maximum number of BoP adjustments for GTLM and GTD prior to its change in the rulebook, which it has now done for the second consecutive year, per the regulations.

The Lone Star Le Mans event at COTA is set for Sept. 17-19.