I remember reading this before but with my long tubes just going in, my question is the long tubes richen the mix correct, does any one know why? and is this correct.

 

anybody?

 

ive heard this, but im not sure how that would affect how the pcm would adjust the a/f

 

On a NON-computer car (think open loop), headers tend to lean out the A/F. On a PCM (controlled with O2's) car during cruise, closed loop the PCM richens up the mixture to compensate. But, at WOT reverts back to the existing tables, so you're lean again.