Torsion Bars... Best Diameter for a Lowered Street / Autocross car?

It’s a fine line. We did 4 post testing at Multimatic with XV years ago. 250-300 wheel rate seems like a happy medium. The problem comes when you lower too much. The moment arm becomes so long we compensate with more t bar. We’re lowering the C of G, but increasing roll at the same time. I found keeping the tire height at 26 helps.