In addition to a reduction in power for DP-based cars, IMSA has made a series of Balance of Performance adjustments to the GTD class ahead of next weekend’s Continental Tire Monterey Grand Prix at Mazda Raceway Laguna Seca.
Both the BMW Z4 GT3 and Porsche 911 GT America, which scored class pole and victory at Sebring, respectively, have been given air restrictors for the first time.
Porsche teams must install a 74 mm air restrictor, while the Turner Motorsport operation, which has reaffirmed its full-season commitment, will run with a 65 mm opening.
All other GTD cars previously had air restrictors.
In addition, the Aston Martin Vantage GT3 will face a 2 mm air restrictor reduction, while the Ferrari 458 Italia GT3 has lost 200 rpm.
GTD cars will compete alongside the Prototype Challenge class in a two-hour sprint race, set for May 4.