i can only summise that a 500 spring has a different spring characteristic due to its weight difference , as the engine mount springs all differ from 500 600 and 652 models , i can only assume that the suspension follows the same line? i have used bis coils on my polski ( cut down ). as visually they show no difference , but with the cut springs find it a very hard ride . also i have 126 rear macphersons on the front which again make it very hard , if i push the car down on the wing i risk denting the bodywork more than moving the car!!! anyhow do you want some coils?