This might be an issue with the mbrp hangers. I had an issue where mine would slide back about an inch and touch the sway bar as well. After trying to reset everything so it wouldn't move three times I ended up just taking zip ties and tying the hangers in place by the rear end. Has held up for...
Here's mine:
Sticker on the door says 12/14 build date. I have about 7500 miles on it, been tuned since 600 and FBO since 6000. Miles aren't that high but I do beat on it quite a bit.