I recently bought an 04' WRX sedan and I noticed that it sometimes make clunking sounds (imagine the sound of popping a dent in a metal panel back out) when turning or going over bumps. It's usually in the back passenger side but it could be making it in the front as well.
It's currently running Eibach pro-kit springs with stock struts as far as I know. My 1st guess is blown struts.
I will put it on the lift and take a good look but I was wondering if there's is specific/common stuff to look for on this particular car that is known to wear out and cause noises after a while.