I should have some results in an hour or two. The head flow is certainly better than an old used up "J" head with 3/8" stem 1.88's but it is still nothing to write home about. To be fair I did open the 318 sized ports on the manifold to the Felpro 1213 size but this manifold is nothing like the RPM series. I bet an RPM would be 10-20HP better than whatever this can muster. J.Rob
