Mustang5L5 said:
As matt said, y heads and z heads are apples and oranges.
Z's are race heads that according for FMS they still need a vavle job, and i think by the time you put them on the car you are looking at 2000+ just in the heads.
Y heads will bring you up to par with Ls1 cars, if that is ultimately good enough for you, get them, if you want to beat those guys, get TWs, Edelbrocks, or afrs.
I know heads are very expensive, i fault no one in not going very expensive.
But remember it costs way more to do this project twice.