Their website doesn't say anything about motion ratios I guess I'm going to call them but I'm failing to see how a 12inch shock can provide 18 inches of travel I'm not trying to be a dick or sarcastic maybe btf can clear up some questions I have when I call them18" are going to be way too long. BTF will tell you exactly what length you need to get 18" out of their kit. but its probably a 10" or 12" coilover, depends on the motion ratio. i.e. a 1.5 motion ratio would call for a 12" coilover to achieve 18" of travel. the higher the ratio, the shorter the shock, but also harder to tune. but like i said, BTF should give you all the specs you need for the shocks when you are ready. They are good dudes and know their stuff.