i'd run it like that, it wont hurt a thing.

 

I wanna try and push it out so it will seal better.

 

i had the same thing happen to me with a BR FMIC (used) and i used a very little heat (not much needed) and an exhaust tip expander from Autozone. Worked and sealed perfectly, i even got a longer coupler to be sure it clamped good. I think it was a 6inch coupler

 

Take it to an exhaust shop, and have them use their pipe expander on it. It circular, and goes inside, then expands to the size that you want and is a perfect circle. You'll save yourself time, effort, and get a better job than some of the other options... Probably cost you $5 and you're good to go...