Couple of differences between ours and GC's:
1) We use a billet aluminum piece for the sway bar end link tabs vs GC's Steel pieces that are just welded together. Looks nicer, cleaner, lighter, and is stonger.
2) We use a high tensile VVS Alloy Springs(smaller coil spring, more compression travel) for our kit vs an Eibach Spring which is a much thicker spring which takes away from the compression travel and are heavier(adds to unsprung weight).
These difference may seem small, but we pride ourselves in the little things to make our products better