STi valvetrain FINAL ANSWER IS?????
 

Is there a conclusive answer out there as to whether or not aftermarket WRX (2.0L) or STi (2.5L) valves, springs, retainers, etc items will work in our heads? If not what about the aftermarket for the EJ22/EJ22T's?

my understanding is that all of our valving is bigger than everything else, i could be wrong, thats just what i have been told by a few subi builders

I don't think it's resolved yet.

Valve diameters are the same for EJ20 Turbo engines to the EG33.

Valve stem sizes are the same.

Valve lengths are different.

there you go

So springs won't work either?

Nope, if their valves are shorter then I'm guessing that aftermarket springs for the EJ's will bind on us. I talked to Ferrea a while back and they said that they would make SS valves (stock size or 1mm over) for $50 per valve. $1200 is pretty steep for our motors especially with uncertainty of being able to upgrade other parts of the valvetrain (springs, retainers, etc)