my opinion.... holly are great if you are able to test them and have the knowledge to adjust them properly. then i would recomend them over any other out there. if you are looking for originality, rochester q-jet has your name on it. if you want something that is easy and fast to adjust, i would recomend edelbrock. i think they are a copy of the rochester q-jets, only with easier adjusting. but a 600 cfm would be too small, go with the 750 cfm for your 400.
