at the moment its a mystery the headers I found out were 1 3/4 to 1 7/8 step to 3 1/2 collector. That for sure would effect the torque band I believe.
I have not seen the result of putting that small a primary on a 530 ish CID motor vs a 2.125 or larger. But I am sure it would reduce the peak HP and rpm it occurs at. But that rpm range is strange.
As mentioned by others, I would just put it in the car and do a couple days of testing with different shift points and your (larger) headers. It still made good HP on the dyno with those little headers.
