Installed a set of .960 MP bars in my challenger to replace the original 318 bars. Just wondering if I should expect any settleing (like leaf springs) after I do the initial ride height setup or if they will pretty much stay where the are now.

I put in same bars and they never settled, still the same 5 yrs later.

I've never experienced settling.

The torsion bars don't settle but the front end will depending on how you bolted it together. The correct process is to put the front bushings together snug on the lift and then torque them down at ride height. If you torque stuff together while the car is on the lift (common mistake) then the car will slowly settle over time as the weight of the car twists the bushings. If you put the car together correctly then it should hold the ride height after you drop it on the ground.

Only if your bigger smile weighs more while driving.

I say yes they do, put a set in my Duster years ago and had to readjust them a few times in the first few days.

But then they were fine after that

I cant say one way or another but I'm inclined to think (most) everything changes/settles downward. A person could measure between the bolt on mini rubber bumper/LCA for future reference (not note taking has been my downfall!).