1 3/4" Headers Verses 1 7/8" on a Healthy 408....Is There a Big Difference??

My machinist tells me he built a Edelbrock headed 408 that made 579HP on the dyno with 10-1 comp a 252/260 solid cam with 1 3/4 pipes.

Edit: Should know soon what it actually makes when it runs shortly with the track opening again and competition starting again.