Headers vs Hi-op manifolds

crackedback said

I'd guess the difference would be in the 12-15hp range at peaks between the Dougs and the 68-70 340 manifolds.

Click to expand...

So 1 to 3 car lengths in the 1/4 mile

I think gearing plays a big role, cars with 4.10--4.56 gears aren't as picky on its exhaust