I'm going to be installing sporltines on my base cobalt and was wondering if the bumpstops really need to be cut?

 

no they don't.

 

will my ride be a lot rougher with them not cut?

 

No, it will have no effect. Eibach includes instructions with their springs telling you how much bump stop to cut IF you even have to. My Prokit instructions for instance had bump stop cut instructions that said NOT to cut anything off.

 

I haven't cut mine and I have 20's. No issues with hitting the frame unless I'm doing 70 and hit a pot hole or bump....then its pretty much out of anyones hands.