Do the smaller 4-point roll bars do anything at all to stiffen the chassis?

 

I doubt that it's significant. The key connection point is from the front subframe to the rear subframe, and a 6-point bar will connect those, as will subframe connectors. A 4-point that stays on the rear subframe is going to accomplish far less. Isn't there an autox rule, equivalent to the SFC rule, that says you can have a 4-point, and not a 6-point bar, or it moves you up in class? Same reason, I'd think.

I can definitely notice when I drive w/o the two door bars in my car (leaving it a 4-point) versus when I have them in...

Dave