So….more header talk….this had me scratching my head

Told him I was looking at putting a 1 7/8 tube on this 418. He told me no way, he would even consider anything bigger than a 1 3/4 tube with what I have, heavy car, Yada, Yada.

What was the predicted performance gain with the 1-3/4 over the 1-5/8 on your combo?