Can you show a picture of how the front hoop attaches to the floor? Thats the only thing I think might be a pain for rear passengers. The roll bars that I have seen do not take any room away from those in the back since the tubes run along the headliner etc.... Where its annoying is if the down tubes block getting in and out down by the feet. From the pictures you have posted, it looks like the down tubes attach right at that spot where you would put your feet in. If you look at mine, you can see it has zero impact on getting in and out of the back. Its hard to tell from this picture but just trying to get a better feel of the install.
just think .. all the performance your looking for could have been achieved by simply painting the car black! haha sweet car .. good look with the project man .. the craftsmanship in that wing alone is sick ..
