The main difference between aluminum and iron is that the iron heads retain heat(makes more power), the aluminum's dissipate heat, not that they perform better in an equivalent head. The biggest factor is if you run alky, it takes a lot longer to get heat build up with an aluminum head than an iron head,a lot longer than with gas!. Personally, unless I was on weight diet I would run iron heads, besides the corrosion factor is a lot less with iron heads!...Just my worthless .02......