I'm looking at catbacks for the future and I keep seeing the recommendation that they are to be 3in all the way though. However I keep seeing that the tailpipe of these catbacks like the hooker super competitions I looked at are 2.5in, these are the pipes after the muffler correct? Do people normally change the tailpipe to 3in as well or no?

 

they are usually single 3 inch back to the muffler, dual 2.5 inch out of the muffler.

 

Appreciate the info!