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

I absolutely wouldn't spend the time and money to upgrade them. Even if you gained 10 HP and I really doubt that. You'll end up losing TQ in the RPM range.

FYI: I have 1-7/8" headers on a very well built 499 RB and that's all the header that engine needs.

Tom