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.
Still got a code after installing my full race catted pipe. I put a o2 sensor spacer on the downstream sensor and it's been fine since. Didn't need the elbow, just a straight spacer.
edit: OAR shouldn't be dropping, you need tune adjusted to fix that or something.
I have the mbrp street and I had to cut about 5 inches off my full-race dp and about an inch off the back of the resonator and it JUST fits in there now. Also needed to use smaller clamps because there's just no room for band clamps.
I use my accessport to read boost atm. The digital gauge in the dash is nice but I actually use that to show my fuel usage and range because I'm a nerd.