Dave, thanks. Perhaps you can contact Subaru and get accurate and specific info as the answers given beg more questions? (I will try as well)
This is from the site of a UK dealer:
In summary the STi models all have
Reinforced engine mounts
Cast pistons Molybdenum coated
Hollow inlet valves, Sodium filled exhaust valves
Shimless valve lifters ....... http://www.iwoc.co.uk/jpnewagesti.html
If STI has MY03 2.0 forged pistons, why does rallyspec only offer cast ones?