Both the GT Daytona championship-leading Aston Martin and recent race-winning Dodge Viper have been hit with Balance of Performance adjustments ahead of next weekend’s GT-only Oak Tree Grand Prix at Virginia International Raceway.

The Aston Martin V12 Vantage has been given a 1.0 mm reduction in air restrictor and 250 less RPM, while the Dodge Viper GT3-R gains 10 kg of minimum weight, receives a 3 mm smaller air restrictor and a 200 RPM reduction.

The adjustments come in the wake of last weekend’s Continental Tire Road Race Showcase at Road America, which saw the Riley Motorsports pairing of Jeroen Bleekemolen and Ben Keating break through for the No. 33 car’s first class win of the season.

TRG-AMR’s Kuno Wittmer and Christina Nielsen, meanwhile, finished second, with Nielsen having taken over the lead of the drivers’ championship.

No changes have been made to the fuel capacities of the Viper and Vantage, despite both teams having lobbied pre-race at Road America over concerns of neither car making the 60-minute minimum drive time on a single stint.

IMSA reduced the minimum drive time for Road America to 50 minutes, with the new limit remaining in place for next weekend’s two-hour and 40-minute GTLM and GTD-only race as well.

In addition to the BoP adjustments to the Aston and Viper, the Audi R8 LMS has been given a larger refueling restrictor, with the Ferrari 458 Italia GT3 facing a slight reduction ahead of the VIR race.