I may be completly wrong but I think a weld in bar would hold up much better. To get through the floor it would have to tear the welded plates out am I correct? Where in a bolt in bar the plates could distort much easier and be pushed through the floor with no welds trying to hand onto them? Just thinking with the keyboard here lol.

I know the place that built the mustang above. I am willing to bet the roll bar was chrome as well as the bolts that held it in .