Is there a hp rating or a chart that we could reference for the 2-1/4", 2-1/2", and 3" pipes,or is there just an understanding that if you have so much hp that you should run a certain size pipe?

I too am considering a larger exhaust pipe once I install my TTi's this Winter but I would like to understand some reason before I consider swapping out my 2-1/4" system.
Thanks and Bump