vis isnt nesc the best.
The difference is the actual carbon to glass ratio, the type of resins they use, the resin to carbon ratio, the underframe they use, what kinda materials theyuse for the underframe and etc.
If all is right, youll get one hell of a very strong, very light part. I have yet to see a CF hood done perfectly. That said, a hood with a perfect ratio of carbon, no glass, and such, would cost a very pretty penny.