Wow, well i had no clue about that and for that im sorry that exhaust came off of my old car i was told it was a 3in but the guy i got the car from, i honestly never looked because i cared more about the gsr teggy, so that’s more my fault because he was going off of what i told him.you should of called him when you got home im sure he would of taken it back and gave you yours back. once again that’s more my fault from going off of what i was told ,but it’s also everyone’s fault because a tape measurer is an easy thing to use on the spot and there’s def one in our garage