Torsion Bars?

BergmanAutoCraft said

Considering the work you've just completed, you may want to consider upgrading the bars. One of the biggest downfalls of the original design was not enough spring rate. You might want to take a look - Mopar A Body Torsion Bar Set 1.08" - Bergman Auto Craft

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Is there fancy ways of calculating the exact size bar I should get? I see guys running .92 and love them,1.00 and love them, 1.03 etc etc. Should I drive the car and see how it feels and then buy softer or stiffer bars? I dont deciding about things I dont know about :(