On this topic, I'm also curious about which has the greatest overall impact on performance:
1) The lower CG of the coupe with CF roof? (I think it saves something like 11lbs, so I can't imagine it lowers the CG that far?)
2) The coupe's 22lbs less curb weight? (3726 vs. 3704)
3) The difference in F/R weight distribution between the coupe (51/49) and sedan (52/48). So the sedan has 11 more lbs on the front wheels, and 26 less on the rear.
My guess is the the weight distribution is probably the only impactful difference, and even then probably only to a skilled race driver.