Hi,
I've been chasing a cracking sound for some days now, which was coming from the rear suspension. It can best be heard when you move over a small bump and is loudly present when you lift the car on a 2-column lift. It took a while as I was suspecting the sway bar bushings. Despite of them being not well lubricated and pretty tight, they were not making the sound (I loosened the drop links and that did not change a bit) and there was nothing obvious to point at.
I ended up tightening all bolts that had anything to do with the suspension, and found the one causing the problem. It was the bit long bolt that goes through the lower eye of the shock. It was not very tight, so I tightened the 22mm nuts properly and now the cracking is gone.
Apparently it is caused by the inner bits (possibly the cone shaped rings) moving on the lower arm and switching position when the load varies.

Job done.
Theo
http://928gts.jenniskens.eu