If you guys are going to be going faster than before, you may want to take a look at the aero configuration

The WRC body kit was made for speeds <150 so I suspect that you'll be in a different 'envelope' once you get up around 200 to torment the Enzo's and other way high dollar toyz.

I'm not an expert on automotive aerodynamics, but you'll definitely want to keep the flow at the back from re-attaching to prevent lifting the back end of the car.

Not sure if this speed regime has been experimented in a whole lot, so I'm not sure that there is much of a basis for a 'best guess' as to how to configure the car.

Best wishes and let me know if I might be able to help

Cheers