2" to 3" exhaust... Worth it?

I have the book as you can tell plus the engine masters episode backing it up. The overall length will have an effect. How long is the correct length? IDK! To many variables. But what the engine masters show did was the Diminishing returns. A continuation of pipe may have hurt and then Adding some more could have brought it back up. Since the pressure wave can be mathematically figured out, bust out the pencil and paper!!!