Pipe Engineering

[baz-r]

sorry it was only a pointer for others as i seen it in your pic

its not so much of an issue with longer headers as its a harmonic thing thats a complete mine field.

its all because there are points in valve timing (overlap) where both exhaust and inlet are open at the same time (more so with sporty cams) and the exiting exaust gas pulls in the fresh charge. get it all wrong and a pressure wave knocks it back in.