I was at a performance shop and had a peak inside the window of another customers GN that was there for service and noticed a really cool roll cage with quick realease door bars. They had a knurled aluminum or stainless sleeve that was spring loaded at the top that slid down to realease, At the bottom of the door bar was a hinge to allow the driver to get in and out without having to climb over the bar. Does anyone know who makes this style roll cage? Thanks.