I can't hear the noise at idle at all, It has to be in gear accelerating. I have even put it in neutral rolling down the road and reved it up several times but still don't hear it then either. To answer a couple more questions, I adjusted the rockers to zero lash then went .030" or 3/4 of a turn. Yes it's a mechanical fuel pump but I just changed it out and that made no difference either. Could the #7 slip tube on the headers be leaking since it is a slip fit? It seemed like this was a nice fit since it had to be perfectly lined up to go togther but this is the first set of headers I have ever run.