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

Agree. Imo a person would be better off with typical 1 5/8 than 1 7/8.
The diff between 1 5/8 & 1 5/8 to 3/4 step tti was imo a 15-20 hp diff on my 410 combo with 'off idle' tq almost staying the same, 3000 ^ midrange to the top increased.

bearing in mind all those motors are stock stroke. 420 ish inch motor is a different animal from a 340