The only difference between a factory rad and an aluminium one is weight. Unless you have a drag car, save your money and stay stock.. I have ran stock radiators in my street/strip cars, heck even my current 88 c1500 stroker as a factory replacement rad.

Edit: forgot to add. Aluminum is use in high performance and drag cars simple because they are stronger and less likely have high pressure blowout(and of course bigger for more cooling on those 500+ HP engines). If your running nos then i would suggest it, but stock nope.