weight reduction and cleans up engine bay. Every bit of weight couts, therefore affecting performance. top of that, 255 walbro fuel pump upgrade to remove the j line. If it werent for emissions id take that junk out so quick. I sure dont care about the NOx. Actually, id think it wouldnt even make much of a difference cuss 80% of the air we breath is made up of nitrogen which mixes with oxygen and other gases. Come on now, the US can test nuclear bombs, but we cant even have a stupid modified part in our cars. I think its stupid..anyways, one less thing to worry about too when it comes to maintenence. Heck, if i find that the the egr diaphram is ruptured, or the valve stays open, id yank that outta my poopra. Once again, the engine bay looks cleaner with a few less vacuum lines on it too.