So….more header talk….this had me scratching my head
For what it is worth (very little!) the header tests that I have seen where a big header loses power and torque, the too big headers are HUGE.
I have a 440 with two inch headers that runs okay, a street driven n/a small block with custom 2" header that runs okay, and a 454 with a custom 2" header, that is probably too long. I'm not gonna change the custom header cars, cause any possible performance increase won't justify the cost.
The only real experience i have with TOO BIG headers, was a friend's 440 Duster, with 2 1/4, 4" collector headers. It might, MIGHT, have run better with 2", but not enough to justify replacing custom headers. I bet those headers would sure work good on a 572 though........