These are by Performance Springs. They are a must for those with High Turbo boost and/or fitting higher lift cams to the 4EFTE Toyota engines. They are a simply drop in set up using the stock retainers, NO mods needed to fit. Specs are: O.D. = .930 (23.6mm) and the I.D. = .665 (16.9mm) Pressures at 1.345 (34.1mm) = 55Lbs and at .950 (24.1mm) = 140Lbs. They have a Coil Bind/stack height of .865 (21.9mm) These have been cycle tested to 10 million cycles, double shot peened and hot set for long life durability. thats what the spec says of them anyone have the oem spring specs ???