340 HP's vs headers

The 340 I built for the 2010 Mopar Muscle Mag engine challenge made 39HP more going from a set of Hooker 1 5/8 headers to a 1 5/8- 1 3/4 header. And it was not all on the top end either, it made more power everywhere on the dyno pull from 3000-7500rpm. If you want power, ditch the stock manifolds and go with a header.