Whether or not you gain torque and power thru headers depends, I believe, on how you finish out the system. What I mean is that, from my limited understanding of exhaust systems, the size of the terminal pipes will directly affect torque and performance. According to Leo Santucci, an expert on later Chevy inline 6s, it is better to err in favor of smaller rather than larger exhaust pipes ("Chevy Inline Six Power Manual"). I was just reading this section this morning.
So headers, properly installed and configured, on an inline six cylinder Chevy engine will give you greater power and an increase in low end torque, depending on your cam choice. I plan on running 1 3/4" duals w/Flowmasters behind my .060 over 292.
-ftyler
