X pipe or H pipe, again

oh boy..lots of back and forth info..maybe they do make power ..maybe they don't?
Nascar engines...358 ci, 850 hp / 10,000 rpm open headers...noise reduction or more power?

"go ahead if you want to, but an H or X is a total waste of time" ...Joe Sherman Racing Engines

"We have dynode many and there has never been an increase in Hp with an H or X,but some
did have a reduction in power"...J.Klein,Packard Engineering