Unfortunately you'd most likely have to get coilovers. I even spoke with the guys at koni and they said they don't have anything in their R&D for the sonic which honestly sucks because the cruze shouldn't be the only car to get the performance treatment when this is the same exact platform just a smaller and lighter weight car.
That sucks. We'll I think I'll just hold off for a little bit longer or maybe just go with the Blistiens
I don't think bilstein's are even made for the car. ... I almost want to have a giant pole started for anyone interested in Koni, KYB or bilstein and send any of those 3 companies on the demanded interest in their product for the car since we are in need of an aftermarket replacement that isn't coilovers.
It you head over to Bilstein's Bilstein, Innovation and High Quality Since 1873 and do a search for Sonic shocks they have the following message:
"Thank you, your search will affect future product development at BILSTEIN. Unfortunately, at this time we do not make any products for this vehicle."
Now if every Sonic owner does a search on their site multiple times a day from different devices...
Just to play devil's advocate.... What's the advantage to replacing struts and shocks and springs over a coil over set up?
Cost is going to be about the same... And separate parts aren't designed to work together...
My first Honda 'cross set up was Neuspeed springs and Koni shocks/struts, but my Tein coil over upgrade was WAY more adjustable and only slightly more expensive.
it's not the size, it's how you drive it....