I've also heard of a cryogenic procedure performed on all sorts of
items
WR>> that increases toughness and wear resistance; I wonder if this would work 
WR>> aluminium cylinder heads...

But onto aluminum, you know he might have something here, how about
hardcoat, ie thick hard anodize.  In the world of rocket science about
here every bit of aluminum subjected to wear or intended to resist
corrosion
recieves such treatment.  I'd bet under $100 a head and might make em
last forever.  Also makes em non-conductive on the surface, ie should
not corrode?

John