Billet heads.

Not really. Things I have planned/ideas for:
Titanium shift knob
Titanium alternator pulley (like an idiot, I dropped my alternator and bent the steel pulley)
Aluminum radiator mounts (stock ones damaged in wreck)
CNC my logo/"team" name on the trans block off plate
Mount for the Y block and FPR on the front of the manifold
Mount to put the coolant header tank on the 818 frame (similar to the mount I did for my WRX putting the header tank on the strut tower)
Mount for a Subaru S202 wing blade

Other stuff as I get ideas.