So I made some assumptions. One assumption is that your cam is ground on a 110 LSA. Another is a 2.08 intake valve. From my guesses you should be on a 107 LSA and probably be installed on a 107 ICL and I think a 106 LSA/106 ICL wouldn’t be bad either.
The other thing I saw and forgot to mention was you have a 7 degree split between your intake and exhaust duration. I know that’s been all the rage for 20 years or so, but I think it’s a bad way to make power. It’s another one of those things that make a header numb. I know Billy Godbold said some intersection things about duration splits and the overlap triangle in an article. I know I have it here somewhere. Finding it…that may be an issue.
I also assumed you have W2 heads. The exhaust port on those is too big, as is the valve. IMO, you need to a single pattern cam, probably 272-274 @.050 and put it on a 107 or even a 106 and install it straight up. IMO, then the headers would have a big effect and the power curve would be fatter off the converter and in the gear changes.
I’m going to look for that article and I’m also going to enter your cam numbers into a really simple program I use and see what it looks like.
Just my opinions on why a header change didn’t make any difference on your engine.