offroad x pipe

Yes if you put in an off road midpipe you will need to get either some MIL eliminators or a handheld tuner.

MIL eliminators modify the O2 signal so that it's within the parameters that the ECU wants to see from those sensors.

With a handheld tuner such as the Diablo Predator or SCT Xcal2 you can just turn those rear sensors off and then wouldn't need the MIL elims.