TORSION BAR ADJUSTMENT

Nothing changes with spring rate by adjusting the torsion bar bolts.
Completely agree. the only way to change the spring rate on a streight torsion bar is to shorten it, thicked it, or use another type of steel. A coil spring is also a form of torsion bar. If you cut out a coil you lower the ride height but you increase the spring rate because you have shortened the overall length of the torsion bar.