I put myself out there as an example of a reasonable expectation...
"IF" I can run pretty much out of the box I would expect to lose around 50 lb of weight off the front of the car? I think a reasonable expectation LOL
50 pounds is not unreasonable.
I would expect better heat dissipation and distribution and with a tall enough gasket be able to possibly use a little less octane in my fuel?
Aluminum won't do a thing for knock resistance. If you plan on lowering the compression with a thicker gasket, you can do that with your heads. The case can be made that aluminum will lose some power to cast iron.
And the performance enhancement I would hope for but not completely expect this to gain a couple two 3 miles an hour in the quarter mile over the stock iron heads?