Chassis shoulder hoop height

I'm building a new FED chassis and no where in the SFI spec does it mention the shoulder hoop height in relation to the drivers shoulder height. Does I need to be level, above or below the shoulders of the driver.

 

i went through this very excersize. after studying lots of pictures, and the design of my RED. i made my fed shoulder hoop with the top of the top rail pretty much level with the top of my shoulders.