TaySTi

since I had prodrive springs fitted to my 05 STi (which was around 8k ago) I've noticed a slight creak which sounds like it's coming from both the front & rear nearside suspension. apart from the sound there aren't any other symptoms or issues. car is also fitted with f&r strut braces. I can only here it at very low speeds, usually just before stopping at lights and junctions, or in very slow traffic jams. would be interested to know the cause. any ideas?