RS,
I went with DJM suspension, they retain the factory shock and strut. For the rear you get shock extenders, shortened springs and a new trailing arm mount. For the front you get new lower control arms with updated ball joint and twin sleeve bushings. I installed this kit on my LTZ and at first did have error lights for the suspension, to correct the problem I had to shorten the height sensor arms (located in the rear and there are two) by 22% which came to 1 inch. Since then after alignment and yes the vehicle can be brought back to factory alignment with ease, the vehicle handles very well, and ride quality is damn near the same as it was from the factory. All in all I'm very pleased with DJM's Calmax kit.