Regarding which car is fastest, usually it's the one best driven.
However, being lighter and shifter could help under some conditions. If you're so worried about being faster, spend your time and money on wheels, oils, o-rings, diff balls and track time. This, without any doubt, will give you the best ROI.
In the other hand, I don't think that a carbon fiber chassis will cause any issue, unless you run at a very bumpy and slippery track, where maybe you'll prefer the stock.
For the bling factor you may agree that carbon fiber is always a nice touch, isn't it?
