When going over bumps or uneven cobbled roads i get some sort of rattling/slight knocking from the back end.

Its an 06 wrx. Is there anything specific thats a common fault on these like anti roll bar bushes or something like that?

Any help would be great, cheers!

 

Sounds like the infamous 'strut clunk' thats plagued many a subaru owner including myself!

 

Nowt u can do. When i had mine I swapped out the rear struts because of clunking and one had a failure and saying as they were born at the same time made sense to do the pair. And was always a chirpy knocking noise. Just turn up your radio or put a louder exhaust on haha

 

There is the regrease nipple mod, check YouTube or just spray some white lithium grease onto shock as I have and seems fine, but it's only a tempory fix.
Common fault. Or replace with coilovers

 

Its due to the inverted design of the dampers and the poor quality oem grease inside the dampers, turning hard and waxy and not properly lubricating the damper properly.

As mentioned above a grease nipple can be added to solve the problem