stock injectors and afm ahould do around 280rwk before you come into too much trouble. I bought 540cc injectors for my car as i dont want a grenade setup
as for the afm's..., dont qoute me on this but i think the standard r32gtst afm's have the same plug as the rb26.
i read this somewhere a while ago. they are the same size as the gtr afms too, if this is the case they will do 400rwhp.