I'm going to put my stock catted H-pipe back on my '03. I installed the Dallas Mustang MIL eliminators when I installed the O/R H-pipe. Will I need to do anything to them so that the O2 sensors function properly back on the stock pipe?
No you don't have to. U can leave them on or take them off. As long as ur car is in good working order and all the sensors work properly, then it should make zero difference.