This is all I could find about it on their website:Beautiful car, wouldn't mind taking a few laps in it. What mods do they make to the motor or are they required to run stock?
Stock engine. Just has a tune for race conditions along with less restrictive exhaust and 58mm restrictor (which they've run since the debute at Watkins Glen). There has been one (1) BoP change to these cars, and that was after CTMP, which was an added 50lbs.They didn't do quite as well; I've read they were hobbled by some sort of engine restrictor... starting this race.
IIRC, the M3 also has a restrictor.Right now, only the Z/28.R and GT350R-C have intake restrictors.