New 3" exhaust with 2.5" Tailpipes

Someone posted about 3” into 2” a few weeks ago. I think that is too drastic but 3-2.5 might actually help. Seems Engiine Masters did a test like this. Dont remember the results.
If air expands when hot then it makes sense the in contracts when it cools and wont require as much volume . It would be a interesting experiment to place temp sensors at various points of the exhaust to see how much it cools.