The elastic region is those whole spring movement just about until it breaks. Just before it breaks, the spring will not go back to it normal position it will be permenently deformed and changed. Depending on the kind of steel and treatments.
The elastic region for our T-bar would go way beyond where the bump stops on our cars are. So it all falls in the elastic region of that metal.
I added rear bar with a stock front bar. Good for autocross and gets the car to rotate. Fine on the street.
Now just before I went out to willow springs race track this May I added a front 1 1/8 sway bar. The professional instructor, Bob Reed with the badass handling red 68 Cuda that's been in Car Craft, drove my car and said he thought it still had too much rear bar and he'd not run the rear bar. That's on my specific car. But he did say with his personal driving style he didn't like much rear bar/roll couple.
I think it's safe to say I made a good choice adding the front 1 1/8 sway bar before I went out on the road course.
But again, I've added front QA1 shocks. I'm playing with those now. That might change things.
I think in an autocross, slower speed, tighter course situation more rear roll couple is needed than a road course.