If you want to see it, get the engine on a dyno. I’d say you can test headers on a chassis dyno but swapping headers in the car is a genuine, over the top battle Royale PITA.
It’s probably easier to pull the engine and put it on the pump to test headers.
BTW, what’s the LSA on the cam? With only 4 degrees of split you SHOULD a make more power with the bigger headers.
