Turbo Pro Muffler - Optimal Flow, No Drone, No Resonance

Looks like my last post was deleted but I was asking if the MVT16 mufflers had 3 inch inner pass tubes or are they just a 2.5" muffler with 3" ends on them? Just wanted to make sure. Thanks.
Edit: The 3" turbo pro mufflers do neck down to 2.5" internal tubes