I am installing a complete S&S exhaust and in the description on the S&S site it says that the head pipes come with 18mm O2 sensor bungs. What size are the stock O2 sensors? Do I have to change the stock sensors? Thanks for your input.

 

Are you referring to the power tune duals? If so, they have both 18mm and 12mm bungs. Your O2 sensors are 12mm and you will use the supplied 18mm bung plugs to fill the holes...