I went ahead and did the math...
Stock B & E body torsion bars
.86 diameter 102.4 pounds per inch wheel rate
.88 diameter 112.3 pounds per inch wheel rate
.90 diameter 122.8 pounds per inch wheel rate
.925 diameter 137.0 pounds per inch wheel rate
Firm Feel B & E body torsion bars
.845 diameter 95.4 pounds per inch wheel rate
.88 diameter 112.3 pounds per inch wheel rate
.94 diameter 146.1 pounds per inch wheel rate
1.00 diameter 187.2 pounds per inch wheel rate
1.06 diameter 236.3 pounds per inch wheel rate
1.12 diameter 294.5 pounds per inch wheel rate
1.18 diameter 362.9 pounds per inch wheel rate
Many people highly recommend Firm Feel torsion bars.
Firm Feel has done the work to make sure that the hex ends are correctly indexed (clocked) on larger than stock bars, so that you don't have ride height issues after installing them.
I notice that these rates don't quite match the Firm Feel advertised rates.
http://www.firmfeel.com/b_body_mopar_torsion_bars.htmlMy guess is that Firm Feels lower control arm measurement is about half an inch longer. Perhaps they measured all the way to the end of the lower control arm, instead of stopping in the middle of the ball joint mounting hole?
This illustrates why it would be a good idea to calculate the rates if you're comparing torsion bars from different vendors. How they measure things can affect their advertised wheel rate.
FOR THOSE OF YOU WHO ARE MORE EXPERIENCED, IS MEASURING TO THE END OF LOWER CONTROL ARM, INSTEAD OF TO THE CENTER OF THE BALL JOINT MOUNTING HOLE A BETTER METHOD?
