skewing the dyno??

One of my favorite dyno claims was changing from a set of 1 5/8 hookers to A body tti 1 5/8-1 3/4 steps headers and a pick up of 45hp was observed.
Were there bananas stuffed in the hooker collectors?
Might want to hook up that 8th spark plug wire when running the hookers.

It's easy to mess with correction factors, whether software or mechanically.