rear sway bar recommendations

One of my favorite photos illustrating oversteer.
Both cars were limited to factory suspension (class rules), but the rear tires of 23 are nearly flat resulting in the oversteer seen. In autocross, understeer is often driver induced (turning too late, entering too hard, etc.)
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By flat what do you mean?

Rear tires look like the sidewall is folded over, at least it appears the sidewall is shorter than the front tires.

I added a rear sway bar, already had front swaybar, Bilstien, bigger torsion bars, and the passenger rear tire would ever so slightly rub the spring when cornering hard left.

Thinking the rear bar was keeping the car more level, therefore rear tires took it.

And with 275/60/15s, a 6.5" sidewall, it's gonna give I'm sure.

I've found Mopars have the right rear wheel ever so slightly closer to the spring.
Fwiw, I switched to bbp axles, which move the axle flange out enough where the tire doesn't rub at all now.