cat and exhaust

[paarman97maro]

Hey guys, I just have a couple questions/concerns about a project that I wanted to pursue. I have been trying to sell my hi-flow cat for a couple months without success, so i was thinking about putting to use on my car. Right now the only thing I have done with my exaust is get a new muffler that splits into dual. The stock cat is 3" in and 2 1/4" out.. the cat that I want to put in is 3" in and 2 1/2" out. I bought an adapter that goes from 2 1/2" to 2 1/4" so that it would fit. Im just wondering am I going to have to program my pcm, or do anything other than switch out the cats. And does anything think this is a worthless attempt? I just want some opinions on what you guys would do, I'm planning on doing it on friday, but just let me know some things i should be concerned about, or any other information I should know. Thanks guys