1 3/4" Headers Verses 1 7/8" on a Healthy 408....Is There a Big Difference??

perfacar said
the car was driven on the street at times, was not radical in any way. 273 had a small cam, 244 dur .425 lift.advertised dur.

how did that fairly stock 273 engine cut off 4 tenths just from switching 1 5/8 header to 1 3/4 ? did you rev it to the moon ? tell us the secret . lol