Heading into the third round of the Continental Tire SportsCar Challenge at Mazda Raceway Laguna Seca, IMSA has released a handful of Balance of Performance adjustments in both the GS and ST classes.

The biggest change comes to the GS class-leading Chevrolet Camaro Z/28.R, campaigned by both Stevenson Motorsports and Mantella Autosport.

The Z/28.R will have a 75-pound weight addition (now minimum 3,575 pounds) and a 3 mm air restrictor decrease (now 65.0 mm).

Stevenson’s pair of Camaros finished 1-2 at Sebring last month, and finished 2-3 at Daytona to open the season.

Technical details on the new Ford Mustang Shelby GT350R remain TBD, as neither the manufacturer nor its technical partner team Multimatic Motorsports has official confirmed its race debut date.

In ST, both the Porsche Cayman and Porsche Boxster have had their restrictors finalized, with both assigned to have a 50 mm flat plate. The restrictor size was not listed in the initial car technical regulations released in January.

Additionally, the new Audi S3 has its maximum boost pressure established (1950 mbar Absolute), the Honda Civic Si has had a 1-gallon fuel capacity increase to 18 gallons, and the new MINI Cooper JCW has had its technical details locked in (18-gallon fuel capacity, 2,520 pounds, 2000 mbar Absolute maximum boost pressure).

The Mazda Raceway round runs on May 2, more than a month after Sebring and with more than a month until Watkins Glen.