I Tow a fair amount, so I didn't want to soften the rear suspension any. I actually added AirLift 5000 ultimate kit to mine so I couldn't stiffen it up some when needed. Stock was fine, but definitely wasn't too stiff. I have a bed rack, metal roll up cover and I always have stuff back there.
But my truck had plow prep package with 6000# front GAWR. The included torsion bars were 84745489. Which from what I could gather is the same bars that come on a Duramax with a plow package. Duramax is 900lb heavier in the front end, lol. A little much for my truck that will never have a plow and the lighter engine. That's why I went with the comfort ride bars. They made a very noticeable improvement on mine even with the oem keys turned up. Tows and hauls the same. Just doesn't bunny hop and beat you to death on big bumps now. Still rides like a HD, but is what it is.