A very late reply, but a note about the Koni yellow adjustable substitute (looking for a softer ride) that also requires washers on the sides. The Koni and maybe the Bilstein has a larger hole than the OEMs. Is this not considered a problem or will good bolt torque keep the shock from jerking up and down in the, now oversize, shock hole?I had these rear shocks installed today: Bilstein B6 Performance Series 24-171687. $131 each shipped from Summit Racing, arrived the next day: Bilstein B6 Performance Series Shocks and Struts 24-171687
A local shop installed them for me for 1.5 hours labor - very reasonable. They do require several washers to fit the Bolt, as the bracket on the swing-arm of the Cruze was apparently considerably narrower than that on the Bolt. It took eight 9/16" stainless washers at the bottom of each shock to fit properly on the Bolt - see the image.
The resulting change in handling of the Bolt is very gratifying. Where my unmodified 2019 always felt reluctant to turn into a corner during enthusiastic driving, the car now feels much more willing to take a corner, there is no longer a need to adjust the line in mid-corner while the car rolls back upright, and on corner exit you just straighten out smoothly.
There is very little difference in ride - bumps are really no more noticeable. I credit Bilstein for this, as their gas-pressurized shocks are known for taking small pavement irregularities in stride, and the result is generally a better ride than Koni Yellows I've installed over the years.
Because these shocks are gas-pressurized, they do increase ride height slightly. I measured the rear wheel arch height before and after, and found a negligible 4mm increase, as I expected.
It's a great mod - makes the car feel almost BMW-like - highly recommended.