I have a b6 a4 1.8t with stock (non-sport) suspension and i was wondering if i put a new set of ultra sport 18" rims on if i would still need to lower the car or the larger rims would decrease the space between the top of the tire and the wheel-well. Thanks

the same as before, or your speedometer would read the wrong speed. If anything else, the optical effect is that your gap would seem larger than before.