Probably the easiest mod you can do to the Regal is the rear STB. I purchased this bar for $10 from a GM dealer. The only modification I needed to do was make the mounting hole a little larger which you can see in the pictures below. My car has a factory installed bar in the engine compartment, so I matched it in the trunk.

When you pull back the carpet in the trunk, you'll see the three bolts for the struts, use the innermost bolt.