My X5 has sport suspension, when my air bag gave up, (sounded like a flat tire!!) I figured, i have sport seats, sport suspension (thicker sway bars etc) but no! i dont have sport air springs!
the sport air springs are a bit shorter when installed (i have both comfort and sport springs)
The connector on the sport bag is different than the one on the comfort bag. the arnott bags come with a new clip, i had to test fit it to make sure it would work, it did, had to press it on pretty hard, but it fits!
It is possible to install either bag easily ! most have the comfort bags (as verified by my supplier! he had to double check my order! ) when i discovered i had comfort springs back there, and i ordered the sport ones, i had the same questions!
turns out the sport springs are a bit stiffer, (if an airbag can be stiffer!!)
they lower the back of the truck down a tiny bit (i would say less than 15mm (3/4 inch), they dont make much difference in ride quality as far as i can tell.
psychologically they make me feel like i am going faster!
whether or not they affect aerodynamics i dont know!

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2003 X5 3.0i (02/2003) sport package, Sapphire black metallic / Black Dakota Sport seats. compass mirror retrofit, trailer hitch retrofit, Prodigy P2 trailer brake controller installed, PDC retrofit, Lumbar support retrofit. heated rear seats retrofitted. Running boards retrofitted and subwoofer install in progress. 4.8is Brakes installed front and back. Bluetooth TCU installed, Rear Fog lights installed. Retrofitted reclining rear seat backs.