FIA Spec does not mandate against positive angles and in fact, for the last number of years, even uses a positive shoulder harness angle on their sled tests. As said before, this belongs in a different thread, specific to the subject. I do not have time today, but will put together the people I have dealt with, the facts they use, the business angle that has kept some companies from moving forward, and some pretty practical diagrams to show why we've made the decision to stop using down angle mounting in our vehicles. We shoot for a few degrees up for the racing we do. If there was a sanction spec that strictly mandated straight back or down, we'd use straight back. I would NOT build a car for myself with a down-angle, but that doesn't mean I won't ride in a down-angle car or even bitch about down angles. I will bitch about non-straight belt lines however. That's it for me, I'm out of this thread unless there's updates from Matt or Nick.
GET WELL QUICK GUYS.