I have a 99 and after I lowered it has a popping noise coming from the passanger rear strut. It only happens when I hit bumps. Oh yea the strut is brand new on that side as well.

 

Did you replace your bump stops on them? That would be the most likely cause of it...

 

yea. It sounds like the strut is lose and clanging but I check everything out and its all tight. Now the other side still has the old strut and its fine.

 

inspect the top of the strut where it sticks through in the trunk and make sure it's all assembled correctly (I.E. matches the other side) if it looks off then inspect a little further, you could also jack up the car and see how everything looks or jump up/down on the bumper and see if you can re-create the noise from the outside....