Typical header dimensions

[Jim Caughlin]

Originally Posted by bert powell

My SS 402 likes 1 7/8" step to 3.25 throat merge collector for what it is worth.

As a header builder who has built several sets for these types of combinations, I think your sizing (1 7/8 with merged collector) is probably correct. 2" primary with 3 1/2 collector is likely too large. I am constantly trying to convince people that they want too large of tube sizes.