Will be following this thread with interest, As I too would like to know these things.
I have an Automatic 1996 220PS wrx gravel express, would love to know what kind of power I can safely run on the stock Ej20G open deck(is 260-280 a safe estimate?) At the moment my plans are Manual swap it and get a Link g4+ with a TD05 upgrade, currently rocking the TD04 factory. Not after massive power just want a nice daily, I hear the TD05 kicks in a bit later, might help fuel economy and top end. TD04 is responsive and pretty fun in the low end though.
Would also like to look into a turbo back and intake at some point, though i am hesitant to install these before getting a G4+ so i can safely tune for them, as i dont wanna harm my engine.