Hi all, need some advice on what this could poss be...

I own a series 2 ERST. Its been lowered bout 35mm on adjustable spax. Ive now started to hear a knock coming from the passenger side at the front. Anyone had the same prob??? It only seems to happen when I go over small holes in the road. It doesn't do it going over speed bumps...

Very frustrating...

CheeRS for any help