For example: Land Cruiser coils used for a rear lift have a high spring rate, so they are not stiff. The OME coils are designed majorly with expidtioning in mind. So they do add a little stiffness to their coils just to help manage the extra weight. And another factor to look at is the way the lift is designed. In order to work with our vehicles, sometimes the spring has to be close to the same size as the stock spring (I know that OME coils are like that). And that means, in order to achieve the lift, the spring has to be stiffer so it doesn't sag under weight. Also, once again take into consideration that when ARB designed the OME suspension, it was meant more for expeditions than rock crawling and high articulation.