This is just my .02, but if you are trying to decide between alumium or iron heads, don't automatically assume that an aluminum head will make more power than an iron head. In fact from everything that I have read, eveyone that I have talked to, and my own limited experience, if all things are equal ( port size, port shape, and valves etc) and the only difference is the material that the heads are made from (iron or aluminum), the iron heads will actually make more power. I know that goes contrary to what most people think, but essentially heat=power, and aluminum heads will dissapate much more heat, much faster than an iron head will. The iron head will hold that heat in the combustion chamber better than an aluminum head. Where the aluminum heads make their money is that they are soooooo much lighter than an iron head, and it takes less power to get less weigt moving to a certain speed. When you are talking about saving that 50-75 lbs on an all out race car where you are trimming weight anyway, aluminum is definetely the way to go, but it isn't necessarily the way to go on a car still wearing the orginal sheet metal. You should look at the setup you want to run and find a head that fits what you want the car to do. Maybe thats an aluminum head, but maybe it's an iron head too.