I think it depends on what your doing, racing in a highly competitive race class and or wanting a high tq per cid (efficiency) for a given hp. But for a weekend burn out machine and non high competition race especially where street ability compromises are an issues. It's better to make power with heads and a smaller cam than the other way around. Plus there's really only a few head options especially if not porting, so basically with a similar bottom end would you like to put a set of 318 heads on it and make 250-350 hp or a set of trick flow and make 450-550 hp.