Big tube header vs small tube header on a stroker

I would imagine that would depend on cubic inch and Rpm out the back along with the length of your header extension

on my 390 (630hp) I changed from 1 7/8 with 3 collectors to 2 inch with 3 1/2 collectors and I didn’t see any improvement on the dyno until 6800rpm to 7500. And it wasn’t much.