[Batman]

Aluminum frees up alot of power and makes it rev happy, but the cost is really fast choppy engagement because there is no inertia from the extra weight of the steel one. For a true street car I would go with the steel every time, especially if you are pushing moderate power or above. With a more stock car you won't notice the difference as much but get a big or choppy cam in there and life begins to suck. You do gain some HP but what makes it feel/sound so much better is how much faster it will rev