IMO Mopars are for sure sprung way to lite from the factory but...
( again IMO) there comes a point when too stiff of a torsion bar just masks the real issue of the front end geometry not being optimal. Too stiff and you basically have little or no suspension, so the negative movement's don't happen, it's just a bigger go-cart. With Mopar's and any unibody design the whole car is a big torsion bar. I'f you limit it too much in one area it has to flex at the next weakest spot. Popped spot welds, ripped out mounts, broken windshields etc...
Unless your doing some serious high speed/high banked road course racing I'm guessing Firm Feel has us all covered?
If your building a dedicated race car that's a different story, they are a "consumable" and not intended to last indefinitely. "Lifespan" is below being competitive on a priority list. No one builds race cars to last 40 years. Most everyone on here runs our cars mainly on the street .
Just my