BDS Suspension 4" Coil-Over Suspension System for 2007-13 Chevy/GMC 1500 4wd. hese have been specifically engineered to fit the BDS Suspension system and feature pre-tuned Eibach coil springs and an external reservoir for increased oil cooling capacity and nitrogen volume for a more consistent and comfortable ride. These Fox coil-overs are pre-set by BDS for the correct ride height right out of the box, offering easy installation as well as the option to fine tune the ride height to your liking. Fox DSC (dual speed compression - see DSC info below) adjuster equipped coil-overs are available as an upgrade with this BDS System for those seeking additional coil-over tenability in any terrain using the revolutionary DSC technology from Fox. Both coilover options are engineered to outperform out on the road or trail while offering fade free performance to push your Chevy to the limits.