Probably emphasizing a minimum and maximum for the the application.
Sure, but it's such a wide range as to be useless for deciding between stock 2" duals, or very non-stock 2.5".
It's also worth noting that the 67 GT500 428 dual-quad Shelby had 2" exhaust.
But then, even the BOSS 429 had only 2.25".
Something to watch out for is various fads for "bigger is better".
In my automotive life, I have seen fads for bigger
•rear tires. L60-15 was the ticket, and required High-Jackers to clear. Cornering was out of the question.
•coils. More powerful, of course, but large size with cooling fins was equally important.
•carburetors. If a 600 was good, 650 was better, and 750 double-pumpers guaranteed the jump to lightspeed.
•spark plug wires. Summa these things are starting to look like heater hoses.
•exhaust. I've seen pipes on Toyotas that would do a Peterbuilt proud.
There's a point of diminishing returns on size, for example, a 3-row radiator is maybe 50% better than a 2-row, but a 4-row is only about 10% better than a 3-row.
So, does a 302, even a really hot one, really require a coil four times as powerful as the one on Mickey Thompsons 427 Hemi Ford Thunderbolt?