Yes, you are right. Inlet is stepped up to 3” just before the res starts. Same as the Borla x pipe. Also, This is meant as a direct replacement for the x pipe that comes with the Borla atak and s-type Catback systems. Inside, it has an H pipe (not sure though). Pics attached!So the inlet is 2.25 stepped up to 3” right before? And what’s the inside view look like? X pipe or straight through?