Chris, purely from an aesthetic point of view, you might consider laying the hoop back slightly. When the bar is straight upright, depending on other factors (windscreen angle, roll hoop thickness, even down to paint colour!) they can sometimes look a little odd.
When the hoop is laid back a little, it gives the car a more balanced appearance. A number of people mentioned that my car looked "fast" standing still but couldn't pinpoint why eventually commented on the way the rollbar flows back with the windscreen.
Too much layback and it looks stupid though.....
It's all about balance
Craig Marsh