Usually there is. The bigger the baffle the more free flow they become. Some larger are usually for bigger inch motors they way I understand it. Dolt is probably more versed on it than me.
tourbox
I put full bore on my Tour Classic with 2” baffles. I got em from J&P cycle. Very low toned and they sound great. When I first put them on I wasn’t too sure about the loudness. Not quite loud enough but after about 500 miles they sound just right without getting too loud. No popping on deceration or when changing gears.
last year I changed out 1.75 to 2.25 in baffles in my slip-ons on my softail. The exhaust was not louder but the tone was deeper, more pleasant sound to me.