does anyone out there have the sport package? i have an x5 4.8i with 21" wheels and the sport package. the sport button does absolutely nothing. i can't tell. it feels like it rides in sport mode (or stiff) all the time. i've even been in an x5 4.8i loaner from the dealer and the sport button does nothing on that one either. what does it do? is there an aftermarket spring setup that will cushion the ride with the sport button off and stiffen the ride with the sport button on?