It's not constant it only happens at speeds in excess of 25 mph. But I'm thinking it could be a shock or spring. But I recently had a catback put on could it possibly be one of the hangers or something associated with. I have no idea what it is but I'd like to hear your thoughts and possible fixes. Oh btw 08 tl-s 5AT

 

Idk why I forgot to put his in there it happens when hitting a bump in the road at speeds in excess of 25mph