help guys.............

I fitted 30mm lowering spring to my car and once fitted it dropped 23mm....the car is a SPORT model A3 TDI SPORTBACK.

Ive noticed a faint knock when coming on and off speed humps,ive replaced top mounts and knocking is still there and ive replace both anti-roll bar drop links........

could it be the anti-roll bar bushes? also ive heard that you have to replace the anti-roll bar as you cant buy the bushes is this true?
This has only happened once cars been lowered.

What could it be?

A3 2.0 TDI SPORT ---SPORTBACK 5 DOOR----

it only does it coming off or on speed humps........worth trying the arb bushes if they come off separatley.........audi say you have to buy complete arb.