The Porsche 911 RSR has been pegged back after its dominant one-two victory in GTE Pro at the opening round of the World Endurance Championship at Silverstone earlier this month.
The two factory Manthey Porsches have had their weight increased by 25kg ahead of this weekend's second round of the series at Spa under the WEC Balance of Performance rules.
The Porsches will now run at a minimum weight of 1235kg, the same as the Ferrari 458 Italia.
Porsche Motorsport boss Hartmut Kristen said: "We were given a tough penalty for our success.
"From Spa onwards, the 911 RSRs have to line up on the grid with an extra 25kg on board, but our drivers and the team have shown that they are able to respond quickly to changing conditions and with the right strategies."
The two 911 RSRs will be driven by their regular WEC line-ups of Frederic Makowiecki and Marco Holzer, the class winners at Silverstone, and Patrick Pilet and Jorg Bergmeister.
Richard Lietz and Nick Tandy, who joined the two crews at Silverstone as a warm-up for the Le Mans 24 Hours, will be on duty at the Laguna Seca round of the United SportsCar Championship this weekend.
The Aston Martin GTE has been given a 15kg weight break for Spa after it struggled to run with the Porsches and the lead AF Corse Ferrari at Silverstone in the wake of a five millimetre increase in rideheight from last season.
The Vantage was initially allowed a 15kg break by way of compensation, but now has been given an additional 15kg, meaning it run at 1195kg.
Aston Martin Racing team principal John Gaw said: "This is a step in the right direction: our simulations over the winter showed that we needed 50kg to compensate and that the Porsche needed to be 30kg heavier.
"I still don't believe, based on those calculations, that we will be truly competitive at Spa; I think we will be a little bit off."
The BoP for the Ferrari remains unchanged.
Subscribe to Autosport Plus
Register for free