Imo besides lighter weight, the best thing about an aftermarket aluminum head is that they're already little over halfway there when it comes to material removed or how much porting needs to be done to get the numbers everyone considers "good".
No guide kink, guide half the size to begin with, already more cross section, ssr wall bulge/hump non existant, straight wall more straight, tubed head bolt holes as a result. Its work, but a lot less/time.
