I need downpipe/crossover pipe help!!!
So, my roommate has an 02 WRX and he threw a late o2 sensor code because the car has no cat and needs a relay to fool the computer that there is an o2 sensor. Well, that rig, which we didn't do, isn't working anymore. So, we took the car to a good friend of ours that knows whats up with cars and he said the wastegate is sealed off, and the crossover pipe is cracked. We just want to get the car to run reliably on a daily basis. So he recommended to get a new downpipe with a cat, a new crossover pipe, and a downstream o2 sensor. Downpipe I understand, o2 I understand, what is this crossover pipe? What kind of setups are you guys running?