Quote:

The modern Hemi engine uses a manifold that is a close copy of a shorty header. And it will outflow an old log style manifold by a lot. And every header manufacturer still sells a bunch of headers for them and have proven gains. Any header design that offers a performance increase will help make an engine more efficient, which gives more power AND fuel economy. Maybe adding 10 horsepower on a low performance engine that only puts out 230 horsepower doesn't mean much to some people, but increased efficiency should .
Keith



Just to clarify, the 6.1/6.4 manifold is a full on shorty header, the factory 5.7 manifolds are horrendous log manifolds that don't even deserve to be boat anchors.

Dulcich did a test on a healthy 440 for Mopar Muscle awhile back and the results are as predicted, 56HP for the shorties over manifolds, 70 for long tubes

http://www.moparmusclemagazine.com/techarticles/mopp_0106_manifolds_vs_headers/dyno_numbers.html