Hi guys just want to find out, how to tell a classic Sti engine from wrx?

Was told Sti has a fifth injector hole?
Some one else said no, the ra has the fifth injector hole??
Any pointers would be much appreciated. 👍👍

 

The later versions of STI had red inlet manifolds

 

This doesn't have the red ones, as I know about the later versions having these fitted.
but this one has a fifth injector hole, and is a version 2.

 

On a 20 year old impreza with chocolate engine it's pot luck as to what it actually has in it.
The only real way of knowing is to pull it appart. But if it's working fine why bother