managed to pop a pipe off under the passenger side seat area. Looks like some sort of breather, went into a little plastic box. Anyone know what this is? Is it important? Been driving the car and no CEL or loss in performance..

Classic STi 6 wagon.

 

It could be the petrol vapor lines, if so it's not something is be concerned over as the in old car fell and was missing for a year till I noticed and replaced it

 

Phew, I thought/hoped as much, could see that they run towards the charcoal canister. Just didn't want to ingest any water. As I said, car runs sweet as a nut, if anything it pops and bangs more now!

 

passenger foot well?

 

It runs across the gearbox crossmember to the chassis leg, its just a vent for the charcoal cannister

 

Under the car as jay said....