Headers vs. Exhaust Manifolds ~ 'Let The Debate Begin'

Generally,

The 'most' you can gain out of a 'stock' Mopar 340 with the 'best flowing' Headers
is about {+27 Horsepower} @ 5400 RPM's.

A basic set of 'Street Headers' will deliver a >
* Minimum ............... {+10 Horsepower}
* Median Level .......... {+14 Horsepower}
* Upper-Grade Units .. {+18 Horsepower}

This based upon tested Kilopascal {kPa} 'back-pressure' levels.