Here's a link to where Fred posted his basic Boxster aero at 180 kph.
https://www.flickr.com/photos/gtcollection/with/32589573982/
Although it's the stock aero, its a good starting point to see where you want to adjust the flow. Center-line cross section of Speed, Density, Pressure, and Turbulence. Just be mindful that as you bend or compress the air, you add more drag.
Edit: *Deleted the pics, they're at the link and posting them all felt like it cluttered up the thread.