Goldhammer

Got a couple of questions, I have a 95 LS400, bought a year and half ago with 58K. Upon pulling into my driveway or coming down my driveway, there is this loud, deep thump when the wheels go over the curb part from the driveway to street. From what I have read it could be the upper control arm or strut rod arms, can anyone explain in more detail what the strut rod arms as opposed to replacing the struts?

Has anyone tried the Eibach lowered springs? Does it improve handling and how does it affect the ride?