December 12, 2005I have decided to put dual 2.5 inch exhaust from my Tri-Y's back and because it is going to be about 300 dollars cheaper I decided I am going to eliminate my Cats. I am going to order the O2 censor simulators, but I was wonderin does anyone know how many I will need? It is a 98 GMC Sierra with a 5.7, any help or inputs on a better idea for an exhaust system than what I have. thanks
December 14, 2005You should only need 2 of them. They are for the 2 O2 sensors BEHIND where the cats would be.