I have some rather large speed bumps at my apartment and when we drive over them in my girlfriends 00 S it makes a thud sound as you drive over the bump and it drops off. Ordinarily I'd say the shocks are probably shot except she bought the car from a forum member who had aftermarket shocks on the car for most of it's life. He reinstalled the factory suspension that had an estimated 15-20K miles max on it and the car feels responsive on the street and at autocross.

I basically just wanted to see if this is normal and if there's just not enough suspension travel for a large speed bump with factory springs/shocks/struts or if you think there's something wrong. I already tried to tighten the bolts on the shock tower and they're snug, if it's not normal the next step is to check the bolts underneath.

 

There's lots of things it could be. The sway bar mounts may even be loose or binding.