Different size roll bar sizes ?

6 or 8 point bars have to be 1 3/4 according to the NHRA. Kind of a bummer for a guy like 69MOPE who has to install a bar to be legal, but then the car becomes quicker so now you have a heavy bar that isn't really required, but becomes part of the cage.

If you do buy a pre-bent hoop and A-pillar bars, be careful, before I had a bender I did that and the hoop fit nice, but the front bars which were supposed to fit our car were totally bent in the wrong place at the wrong angle. Also make sure to utilize gussets where you cannot get a full weld all the way around the joint.