Currently rocking the Hotchkis Rear bar.
Noticed reduced body roll and more linear, predictable rear “slide/oversteer” when pushing the car hard.
Yeah, that's what I just installed also, Hotchkis #22447R, had the 22mm solid Whiteline bar that I just removed. Didn't like that the Whiteline was in the way when jacking the car by the axle beam, and it was pretty heavy.
Hotchkis is lighter (it's hollow 22mm vs solid 22mm) and fits better (precisely made to fit close on the 2018 car whereas the Whiteline had some minor issues and uses a thick spacer)... not sure what the difference is driving as I've only just driven it on the street this evening, but seems OK.
I will find out on Sunday. Certainly preferred it with the bar as opposed to without, probably about 2 seconds or more difference... Not sure if the weight back there was bad, but trying this one. Actually it's only about 3 lbs (unsprung weight) difference so I probably can't tell, and may be a bit softer as it's tubular. There were people trying a lot of different rear sway bars a few years back, so I was hoping to get some more insight. Also some people ran a bigger front bar instead.