where does it hook up to in the sti? the headers? and if i get new headers later on....do i need to rebung?

 

Yes I would hook it up to the headers (cylinder #3 is the most popular) and if you replace them you would need to tap a new hole. BTW...rebung is a funny word.

 

....the easiest place to put the probe is in the outboard casting 'button' on the drivers side manifold.....nobody wants to mess with the pasengers side manifold any more than absolutly necessary.....

If you have the mechanical wherewithall and no issues with rusted bolts on the heatshield(3 of 'em) or elsewhere....removing the manifold(3 nuts on the headstuds and 2 crosspipe bolts), drilling/tapping it and re-installing the whole thing is an hour or so's work.