I had the very same car, with the very same problem, Most likely oil getting into the intake system and being burned, from high G- forces My GT3 RS gets worked on at TRG and the race in the Koni Challenge Series they run Modified street Carreras to spec for the series. I have spoken to staff there about the problem the air/ oil separator gets bypassed filling the intake with oil. It does burn off and return to regular service, but those engines have had alot of oil starvation problems at the track and secondary shaft failures as well.
You must be getting good at driving, cause thats when they smoke!!
