02 Lancer oz. listen to this.........
 

Okay i just put one a whole new exhaust, new cat. converter and everything. Went to get a inspection today.. the guy ("mechanic") told me the cat was on backwards because the o2 sensor is suposed to go behind the cat.? and not infront? but i still got the old exhaust together checked it out. its the same exact way i have the new one on. and that old one was replaced by mitsubishi due to the re-call they put out.. so i would assume they know what the hell their doing?. so who is right? and i dont think the wire from the o2 was long enough to reatch. any help would be nice.. Thanks.

Well depending if its a monitored cat there should be two o2 sensors one before and one after the cat.

How many cats are on the stock exhaust?

theres one cat. the 2nd o2 sensor is on the cat..