bump stops prevent the shocks from bottoming out, you can get shocks with bump stops in them or buy bump stops seperately, its a really good idea to get longer ones if you use the spacers and want to run off road
I'm surprised that the 2" kit came with new bumpstops. I really can't answer your question, but am anxious to see responses, as I left my bumpstops off when I did my 3 1/2" lift.