Well, I finally got an offroad X pipe for the mach and installed it yesterday. I must say that it sounds MEAN, even with the stock mufflers. I have some flowmaster 40's sitting around, so I may add those in later today. Never the less, the pipe (BBK) has 4 slots for the o2 sensors. The wires on the "pre-cat" sensors reach the plugins just fine, but the back ones do not reach. Are the back ones vital? Or is it alright just to get some MIL eliminators and be done with it? Just checkin' before I move forward.