Not everyone can afford aluminum plus the cost of porting them, nor does everyone want or need aluminum. I'm not saying this from a arguemenitive point but I personally wouldnt use a HP aluminum or a Edlebrock head on the street, as the runners are much too larger for this purpose IMO.
Also Iron will make more power, I know what your going to say, but the aluminums that your going to say are as thick and as heavy as iron heads, and the reduction of flex under high pressures is why they are making the power that they do but then the weight of them is very close to the same.
