When should you upgrade torsion bars?

Are the subframe connectors bolt on? What is the difference between that and adding a sway bar?
Yes there are different brands some are bolt on and some are welded some are both . Choose your poison ! Sub frame connectors tie in your chassis from your gear box mount frame where your torsion bars feed into back to your front spring hangers live. Others will chime in and will give better explanations on both components.