I just got my 2007 Lexus GS430 and I there's nothing wrong with it while i'm driving except this issue that i noticed when I drive over a speed bump, a weird click sound comes from the back. It seems to me that something is going on with the suspension parts and closely when the springs get squeezed this sound happens just like hitting two solid things together. However if I drive very slowly over the speed bump, I hear nothing at all. I don't know if that's related to the technology for setting up the sport or normal norm.

Can any expert explain to me what that sound means?
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