what was said before was right. if the 02 sensor(s) are pre-cat then the engine light shouldn't come on. if the O2s are post-cat then you're SOL.
otherwise .... why? I mean, our trucks are slow. A little less restriction in the exhaust isn't going to help much in that department. And wont you have to pass an emissions/smog test one of these days? To me this just seems pointless. *shrugs*