Going to pick up new S4 Tii housings. I am wondering if I could run two front housings or two rear housings.

 

the difference is the air injection passage, they only get drilled on one side. its no big deal to drill the passage if needed

 

So if I am deleting the emissions and air pump, that wont be a big deal, and ill be able to block it off, or just not drill it? Which housing has the air passage normally?

 

they both have the passage, and if you assembly the engine correctly they face the center iron, the port under the primary intake ports feed it.

we've had a couple of people move to California (with some famous, at the time, cars) and since it will never pass smog without functional air injection these guys got to buy an engine.

up to you, but its best to drill the passage now and then if needed you have the choice.