These Kits regardless only really make any noticeable difference when your at speed as the high air pressure is needed to get the kits to start forcing the car down and so sticking it to the road more! Most of the time its just for the pure sexiness of how they look
But they do make a difference at higher sppeds! in my old car there is a stretch of road that if i went round at 60 the car felt a lil twitchy but if i went round at 70 the car felt more grounded owing to the lotus developed bodykit and spoiler on it!

Good times!