For those running dedicated roadrace cars. Are you running cars level or rear up.
I am currently running my car level at static ride but have found since fitting a new undertray that the car is assuming a noseup/tail down look on straights so assume we are getting air pressure under the front tray.

 

according to carol smith, minimum wheel travel in bump is about 3 inches in the front--with more needed in the rear.

 

I use a slight rake. No idea what it looks like outside the car at 100 mph though.

 

A slight rake may provide some additional downforce. How much is up to your set up. Generally the air traveling under the car will then accelerate out the back of the car producing less drag and a slight loss in pressure under the car, thus the downforce (As the air travels toward the back of the car, it must fill an increasing space-acceleration. Also, air traveling over the car will push down on a raked car a bit more. This is all helped by a stiff suspension setup that will help the front end to stay put during acceleration. This is the same concept as used in a diffuser, or something more simple like the undertray of a Trans-Am car or 1990's GTO IMSA cars. Flat bottoms for the most part, a bit of rake, and a smooth diffuser with a bit more rake behind the rear axle line.